A. An Unwritten Ambiguous Arrangement: The United Kingdom

I begin with the oldest constitution, under which non-statutory powers seemingly receive full constitutional sanction through the Royal Prerogative, a long-standing tenet of the British constitutional framework. The Prerogative, as defined after the 1688 Glorious Revolution, pertains to those powers retained by the Crown and not taken away by Parliament, and is part of the compromise forced on the Monarchy at the end of the seventeenth century.Footnote ²²

For centuries, prerogative powers remained strongly tied with the eminence of the Monarch, an attitude echoed in Blackstone's eighteenth-century definition:

The rise of elected politics and parliamentary power, coupled with the gradual evolution of the Crown into a largely symbolical figurehead, are both expressed in Dicey's late nineteenth-century definition:

This definition emphasizes one important aspect of prerogative: its continuing existence depends on the absence of legislation: no non-statutory powers, even lofty prerogatives, can be exercised when a statute governs the same field. This residuality rule has retained its status as the principal constraint on the prerogative. Hence the idea of a ‘shrinking’ residue of powers.

Historically, ‘prerogative’ refers to a list of specific powers, largely acknowledged by courts but not dependent on their recognition. Some are irrelevant to this article—prerogatives pertaining to parliament and legislation, Crown immunities and Crown privileges.Footnote ²⁵ I focus on prerogatives that are purely executive in nature, for example, the waging of war, the conduct of foreign affairs, the grant of pardon, the administration of the passport regime, and some high-level appointments.

In the British context of an unwritten constitution, almost no one (at least since Chitty)Footnote ²⁶ has dared to present a complete list of prerogatives. Lists are carefully supplemented by a caveat such as ‘it is not possible to give a comprehensive catalogue of prerogative powers’, followed by a discussion of the classically acknowledged ones.Footnote ²⁷ The legitimacy of its exercise remains a constitutional convention, one of the constitutional rules which are considered part of the unwritten constitution of the United Kingdom.

Despite the historical link to the Crown, all ‘executive’ prerogatives, from war powers via the pardon power to the grant of passports, are entrusted entirely in the hands of the executive, with a symbolic assertion of the Crown. Here, then, is the first constitutional source of current non-statutory powers.

The natural ‘shrinking’ of the prerogative due to the general expansion of legislation over the past two centuries has been twinned with a strengthened commitment to legality, under the principles of the sovereignty of parliament and the rule of law, all anathema to arbitrary prerogative. Dicey does hint at the problem of retention of the prerogative—it offers the government ‘large powers which … are constantly exercised free from Parliamentary control’,Footnote ²⁸ but he refrains from calling for its removal. Instead, his emphasis is on constitutional conventions that determine, and constrain, the exercise of the prerogative.Footnote ²⁹ Twentieth-century harsh criticism of executive discretion under legislation, notably Lord Hewart's influential The New Despotism,Footnote ³⁰ has further strengthened the critical attitude, leading to modern-day escalation of reform.

Some prerogatives have thus been duly legislated, as in the earlier case of the Crown prerogative of coinage. Counterfeiting and other such offences were consolidated in the Coinage Offences Act 1832; the current Coinage Act 1971 replaces the Coinage Act 1870, which places all powers in this field in the hands of the Crown, but under statute.Footnote ³¹ The most recent reform, the Constitutional Reform and Governance Act 2010, regulates the civil service and legislates the Ponsonby rule. Still, the prerogative remains central in some fields: the passport regime remains prerogative-based, and the recently declared convention requiring a parliamentary debate and vote prior to committing troops to armed conflict has not fully removed government prerogative in this field.Footnote ³²

The pairing of ‘non-statutory’ powers with ‘prerogative’ powers is unsurprising, since the prerogative does not derive from statute. Prerogative, nevertheless, is really something else. It connotes a shrinking reservoir of powers, deeply embedded in the unwritten framework of the English constitution, and should therefore be viewed as equivalent to powers that draw directly from a written constitution. In their true form, non-statutory powers feed on unexpected futures and statute's intrinsic eventual failings. Indeed, many non-statutory powers currently invoked in the United Kingdom cannot be linked to this historical source of power. Such identified powers include the creation and operation of ex gratia payment schemes,Footnote ³³ the issue of governmental pamphlets,Footnote ³⁴ and government policy-making by contract.Footnote ³⁵

These powers have now been titled the ‘third source’ of power, but not all of those who recognize the existence of such powers have found a source of constitutional legitimacy for their exercise. Certain commentators revert—some with reservations, some quite happily—to an analogy between the State and the powers of a legal person.Footnote ³⁶ The court has joined in,Footnote ³⁷ while the government has unearthed a 1945 legal memorandum and argues that it has always provided a basis of power that is equivalent to these inhered in an individual.Footnote ³⁸ Whether this indeed is the established understanding of such powers is a matter of debate.Footnote ³⁹

Returning to the prerogative, the main constraint set on their invocation, mentioned above, is the residuality rule. Formalized in De Keyser's Royal Hotel, the rule was applied as the main ground for deciding that the prerogative powers to seize property in wartime without compensation could no longer be invoked, even if it had existed, since statutes in force granted compensation in such cases. The rule seems simple enough:

This constraint, however, has always been amenable to manipulation: statutes have been interpreted as open-ended enough to accommodate parallel arrangements, or were altogether ignored.Footnote ⁴¹

The most far-reaching reform in this field has been judicial readiness to subject the exercise of the traditional prerogative to review. Initially, the courts intervened only when the challenged executive action should have been exercised under existing statute, as in the De Keyser case.Footnote ⁴² In addition to the application of this residuality rule, the courts were only ready to decide the question of whether the challenged executive action was indeed part of the prerogative. If it were, that was the end of the matter: a general immunity from review derived from the remaining link between these powers and the Crown. The full subjection of the prerogative to run-of-the-mill judicial review was gradual. Initial judicial dicta, first expressed in the 1960s and 1970s,Footnote ⁴³ were the harbingers of the House of Lords' groundbreaking declaration in the mid-1980s that prerogative powers, exercised under modern constitutional convention by the government rather than the Crown, were subject to the same review applied to statute-based power.Footnote ⁴⁴ In GCHQ, the court was concerned with a delegated power under a prerogative-based order in council; the amenability of review of an order in council itself, the legal status of which remains unclear, was affirmed in Bancoult 2.

The reasoning in both decisions was functional rather than historical. Consider Lord Hoffman's opinion in the latter decision:

Still, both applications failed for non-justiciability. Since GCHQ, review of the prerogative, now seemingly equal to statute-based powers in this context, ‘depend(s) on the subject matter of the prerogative power which is exercised’.Footnote ⁴⁶ In GCHQ, review of a decision concerning an intelligence agency was barred for national security reasons; Bancoult was inextricably linked with national security and foreign affairs elements, the two main fields deemed non-justiciable.

In sum, British courts no longer award non-statutory powers, even those with the ‘prerogative’ imprimatur, special immunity from review, but such powers remain one of the governance tools available to the executive. Some are granted the grand title of ‘prerogatives’, others may have a lesser pedigree. The residuality rule may limit their application, but in principle, the system recognises their existence. When pertaining to non-justiciable fields of action, judicial review will be barred, but this hurdle applies both to statute-based and non-statutory powers.

B. A Written Ambiguous Arrangement: The United States

As in the case of the UK, true US non-statutory powers are powers that derive neither from statute nor from a clear authorization in the constitution. While the main causes for ambiguity in the UK are history and the absence of a written constitution, in the US the vagueness is contained in Article II of the Constitution. This vagueness has helped to fuel a series of ongoing disputes, against which presidents have been able, legally or at least with sufficient political backing, to wield non-statutory powers in certain fields without paying a political price.

A survey of the rich literature on the framing process and the ratification years leads to one certain conclusion: beyond the commitment to the democratic ethos, no clear vision of the extent of such powers can be safely garnered. The shared allegiance to the constitution as the primary element of the new polity, and to the ideal of separation of powers in its checks and balances version was a constant guiding light, but the contours of the constitutional structure were originally fuzzy.

The Philadelphia Convention's mandate ‘to render the Constitution of the Federal Government adequate to the exigencies of the Union’Footnote ⁴⁷ was directed by two forces. Looming in the background was the colonial legacy: in the newly independent nation, popular understandings found any form of monarchy abhorrent. However, the Annapolis resolution was generated by the virtual breakdown of the Confederation structure as a framework strong enough to resolve the problems facing the new nation in the absence of a national executive. The decision to move ahead was, thus, designed to resolve the domestic problems created by former arrangements.Footnote ⁴⁸

Accounts of the long, sometimes tortuous weeks that led to the finalization of the text show that initial drafts were in fact starting points for the overturning, reintroducing, and otherwise turning around of the key elements of Article II. The framers argued long and hard over the Presidential election process, but the minutiae of Article II powers received much less attention and were finally settled by the Committee of Detail and Committee of Style. One telling example: the final wording of the vesting clauses, to which I return below, was the product of the committee of style.Footnote ⁴⁹ The retention of an open-ended Article II may have been driven by certain members, generally supporting an ‘energetic’ executive, but the final version cannot be described as the product of open and detailed reasoning.Footnote ⁵⁰

Underlying this seemingly surprising marginalization of the treatment of executive powers was deep ideological disagreement. The battle between Federalists and Anti-Federalists, who pushed for distinctly different constitutional structures,Footnote ⁵¹ was waged alongside a parallel dispute within the Federalists. Both factions, led by Hamilton on one side and Jefferson and Madison on the other, supported an executive that could rise above normal law in emergencies, but the differences between the theories on the nature of the constitution at large, and executive powers in particular, were far from marginal. These views were fully exposed during the post-ratification era in several famous disagreements. I focus on the 1793 Publius-Pacificus debate.Footnote ⁵² Hamilton strongly supported a powerful presidency: at an earlier point, he advocated the instatement of a hereditary monarch, a suggestion removed later, but his general support of a strong president remained.Footnote ⁵³ In the debate over George Washington's neutrality proclamation, Hamilton found both functional and textual bases for his support of the legality of the proclamation, arguing inter alia that the enumeration of presidential powers in Article II did not derogate from the broad authority granted in the vesting clause; therefore, ‘the executive power of the nation is vested in the president; subject only to the exceptions and qualifications, which are expressed in the instrument’.Footnote ⁵⁴ Madison's opposing, clause-bound interpretation led to the rejection of unilateral presidential power in the issues at stake, the signing of treaties and war powers; if at all, they could have been linked with prerogative, which was clearly not part of the constitutional framework.Footnote ⁵⁵ Jefferson's strict constructionist stance was equally opposed to Hamilton's political theories.Footnote ⁵⁶

These disagreements on function and text set the tone for the future. Indeed, each and every theory of the role of the presidency advanced since, from a limited vision of the president as presider/moderator to the full-fledged version of a post-9/11 imperial ruler, have found basis in the text, in different understandings of original intent, and in constitutional history. In addition to reliance on the vesting clause, echoing the 1793 debate, Sections 2 and 3 of Article II enumerate a renowned list of powers, including the command of the armed forces, the grant of pardons, the making of treaties under Senate advice and consent, and the ambiguous ‘take care that the laws are faithfully executed’ clause. All are open for interpretation, notably the ‘take-care’ and commander-in-chief clauses, which offer promising bases for expansionist visions.Footnote ⁵⁷

Moving from textualism to original intent, the underlying disagreement on the nature of the executive, discussed above, belies any attempt to reach a clear answer. Supporters of both camps have relied on original intent to buttress their normative arguments;Footnote ⁵⁸ original intent, then, also seems to lie in the eyes of the beholder.

A similar result emerges when history is chosen as the guiding methodology. Here, I do not refer to the evolution of executive powers via ‘historical gloss’—this is treated further below—but to reliance on history and practice to support normative arguments over the proper extent of unilateral presidential powers, by showing that the proposed vision is not only superior, but is in fact deeply embedded in the history of the nation. In this respect, too, interpretations of history seem to support members of all camps.Footnote ⁵⁹

Beyond text, intent, and history, scholars have offered functionalist bases for the varying understandings of the nature of the executive in general. The constitution remains important here, though less as a clear authorization and more as a guiding light; a return to the basic reliance on democracy and the separation of powers is evident, alongside arguments concerned with the promotion of values such as accountability, effectiveness and consistency.Footnote ⁶⁰ Yet the same arguments support various normative stances, from ambitious regime change proposals to calls for enhancing presidential centralism.Footnote ⁶¹

The general pattern on the ground has been that of aggrandizement. President Lincoln's actions during the Civil War were retrospectively approved by Congress; his, and President Theodore Roosevelt's ‘stewardship’ theory developed in 1913, laid the ground for subsequent calls for presidential dominance, particularly at times of grave national emergency.Footnote ⁶²

Yet presidents have never limited invocation of non-statutory powers to emergencies. Non-statutory presidential impoundment of funds, used to impose policy directions through presidential refusal to activate budget items, was prohibited by statute in 1974, after a marked rise in the practice.Footnote ⁶³ Signing statements, pronouncements of disagreement with elements of a statute signed into force, have replaced this practice.Footnote ⁶⁴ Presidential executive agreements supplement, if not materially replace, the constitutional arrangement that involve the Congress in the process of treaty-making.Footnote ⁶⁵ Presidents unilaterally requisitioned lands through the nineteenth century and the early twentieth-century.Footnote ⁶⁶ Many of these actions were authorized by executive orders, a well-established semi-formal mode of presidential policy formation, which often does not rely on statute. Other forms, such as proclamations and the memoranda referred to in the introduction, grant the presidential message special weight, but when no statute is involved, they are pure expressions of unilateral power.Footnote ⁶⁷

As for judicial stances towards such powers, it should first be noted that, in comparison with the other common law systems analysed in this article, the president of the United States enjoys exceptional insularity from review in all areas non-constitutional, (that is, when public acts are challenged at the administrative law level), an insularity supported by a strong culture of judicial deference. Paradoxically, despite the fact that, from inception, the president as the head of State was not protected by the aura of monarchy, no move for equating direct presidential action to run-of-the-mill output of administrative agencies, traced above in the context of the UK,Footnote ⁶⁸ can be discerned.

This is not to say that courts have not reviewed presidential non-statutory powers. For some, the now-accepted maxim that ‘the president's power … must stem either from an act of Congress or from the Constitution’Footnote ⁶⁹ reflects a general judicial tendency to invalidate presidential non-statutory power that cannot be linked with the constitution. However, a closer consideration of the jurisprudence shows that here, too, interplay between different attitudes exists; in fact, a general pattern of accommodation is dotted with singular cases that trace the limits of presidential power.

First, courts have sometimes found sufficient statutory basis for presidential action, even when no specific statute was originally cited, thereby fully legitimizing the challenged action and extracting it from the realm of the unilateral.Footnote ⁷⁰

Moving to powers that found no statutory base, the spectrum of judicial stances leans towards endorsement of the president's powers. I begin with the restrictive end of this spectrum. Some cases involve the invalidation of unilateral action, as in the Hamdan affair, in which the court found that no statute authorized the government to convene the challenged military commissions, and that the rules governing those commissions violated the Uniform Code of Military Justice.Footnote ⁷¹ Further, the court's readiness to strike down statutes that were found to grant excessive powers to the president more than indicates that limits to presidential powers also draw on the separation of powers principle as designed in the constitution. In Clinton v New York, the Supreme Court invalidated the Line Item Veto Act, which empowered the president to cancel specific spending provisions, for violating the presentment clause, being in effect a grant of power to amend or repeal legislature.Footnote ⁷²

Youngstown, the most famous decision in this context, should be positioned slightly closer to the accommodation pole of this spectrum. On its surface, the decision should be read as a reinforcement of the residuality principle. Rejecting arguments that relied on ‘the aggregate of the [president's] powers under the Constitution’, that is, the vesting clause, the take-care and the commander-in-chief clauses, Justice Black's ruling that the president could not seize steel mills in order to prevent an industrial action, since an impressive body of statute-law offered channels of action, is a clear expression of the residuality rule.Footnote ⁷³ However, the complex web of opinions conveys more.

The most memorable and frequently used part of the decision is contained in Justice Jackson's concurring opinion. In the first of his three ‘practical situations’, Justice Jackson reminds his readers that executives often act under statute, a truism that could have been excluded from our analysis but for Justice Jackson's readiness to consider implied statutory authorization as a sufficient basis.Footnote ⁷⁴ In his third category, Justice Jackson reiterates the residuality principle, but with a triple twist. His focus in this category is on action that is ‘incompatible with the expressed or implied will of Congress’, a formulation that may further constrain the president, when his actions only impliedly contradict statute. Yet, when such contradiction occurs, Justice Jackson considers the president's power to be ‘at its lowest ebb’, a sufficiently neat formulation for potential future manipulation. Finally, as befits the system, Justice Jackson returns to the possibility of direct authorization by the constitution, a parallel source of authority that offers a broad scope of interpretation that may accommodate presidential action.Footnote ⁷⁵

Justice Jackson's second category offers a rich repository for potential aggrandizement of unilateral executive power. Alongside the president's own independent powers (under the constitution) there exists ‘a zone of twilight in which he and Congress may have concurrent authority, or in which its distribution is uncertain’. In these cases, acquiescence and other modes of Congressional inertia may ‘enable, if not invite’, independent presidential action.Footnote ⁷⁶ Justice Frankfurter's equally famous reference to historical gloss further embeds this mode of aggrandizement:

In another concurring opinion, Justice Clark finds that the Constitution does grant the President unilateral powers ‘in times of grave and imperative emergency’;Footnote ⁷⁸ in effect, he joins the dissenters in this matter. The decision, then, cannot support the rejection of all emergency powers. In conclusion, the overall meaning of this decision is, as many have noted, sufficiently open to accommodate differing applications.

Then there are cases in which the courts decide not to decide, using non-justiciability doctrines (such as the political questions doctrine, lack of standing, mootness and ripeness), often used in challenges to the exercise of war powers,Footnote ⁷⁹ and by denying certiorari, which, inter alia, enabled the Supreme Court to remove itself from the debate over the constitutionality of the Vietnam war and participation in other hostilities, unilaterally initiated by the president.Footnote ⁸⁰ In all of these cases, non-intervention in the decisions of lower courts that upheld the challenged measures could promote consecutive reliance on such modes of action. Other forms of non-interference are found in cases decided on the basis of non-reviewability due to the lack of ‘force of law’ of the challenged measures.Footnote ⁸¹

Nearer to the other end of the spectrum are decisions that uphold non-statutory presidential action by reference to sources beyond the text of the constitution. First in line are the ‘historical gloss’ decisions. Decades before Youngstown, the Supreme Court found long-standing practices, supported by judicially recognized congressional acquiescence evident in oblique references to the said practice, appropriation of funds for its continuation, or simple inaction, to be sufficient justification for upholding unilateral presidential action. In Midwest Oil, the court upheld the decision to temporarily deny access to and use of oil-rich public lands due to a shortage of natural sources, contrary to a statute that enabled free use of land. The court relied on the decades of practice, never challenged by Congress, to uphold this one example of a decades-long practice.Footnote ⁸² Upholding an action that contradicted statute, this decision, then, does not conform to the residuality principle. Subsequent decisions in this vein pertain to foreign affairs.Footnote ⁸³

The most permissive decisions recognize inherent powers that do not directly originate in the constitution, and hence may be free of its constraints. The typical decision is Curtiss-Wright, decided in the 1920s. The case involved the presidential setting of an embargo under and in accordance with statute, but in his opinion, Justice Sutherland supported all forms of executive power in foreign affairs as sufficiently deriving from the sovereignty of the State.Footnote ⁸⁴ Whether this stance would support similar action today is doubtful, but the above survey shows sufficient bases for accommodation.

In sum: without settling the ambiguity inherent to the text of the constitution, presidents continue to enjoy some freedom to act in the absence of statute. Nothing in the written constitution prohibits the exercise of such powers; the system more than tolerates some of them, and the limits on their exercise have yet to be doctrinalized. Two constraints on the exercise of these powers have emerged, albeit in a diluted form. A general residuality principle does exist, but exceptions and competing older rulings challenge its robustness. Secondly, the recent jurisprudence, mainly Hamdan, seem to constrain reliance on unilateral power in cases involving a direct breach of a human right.Footnote ⁸⁵ These constraints, however, are at their lowest ebb in two contexts: when presidents are involved in the making of general social and economic policy, which, inter alia, limits if not eradicates standing of most, if not all, interested parties, and, very much like British courts, when subject-matter sensitivity is likely to enjoin courts from intervention by using non-justiciability doctrines.

C. A Written Balanced (?) Arrangement: Israel

On its establishment, Israel preserved former Mandate law,Footnote ⁸⁶ and could have followed Great Britain in basing its solution to the question of non-statutory powers on the historical prerogative. The possible absorption of the Royal Prerogative by way of inheritance of colonial law was discussed in academic circles,Footnote ⁸⁷ but was never judicially adopted. Non-statutory powers received a somewhat weak base of legitimacy, drawing on a functional basis, in the 1963 El Saruji case. Deciding upon the authority of the Minister of Religious Affairs to appoint and fund a religious Muslim committee in the town of Acre in the absence of an enabling statute, the High Court of Justice ruled that

Using a similar functional reasoning a few years later, the court ruled that the government was empowered to ratify international treaties, again despite the absence of legislative (or constitution-based) authorization. The court relied on canons of international law and on a functionalist ruling that ‘the creation and existence of international relations … are a clear matter for the executive branch’.Footnote ⁸⁹ Two Justices criticized arguments that based this power on Mandate law, emphasizing the independence of the State and its disassociation from the British constructs existing in this field. One of the justices opined that

Formal treatment of the issue was introduced in 1968, in the Basic Law: The Government, a semi-constitutional statute that was later recognized judicially, with all other Basic Laws, as enjoying constitutional status.Footnote ⁹¹ The Basic Law includes a short provision that both allows and limits the invocation of non-statutory powers:

The provision was intentionally designed to provide a final and definite answer to the problem of non-statutory powers. No information on the inspiration for the drafting is available.Footnote ⁹³ Since 1968, then, non-statutory executive powers are exercised under a formal source that seems to offer a structured solution.

As in the other studied systems, reliance on non-statutory powers in Israel is not a rarity. State funding discussed in El-Saruji is but one example. Several government ministries rely extensively on non-statutory powers. For example, the Ministry of Immigrant Absorption, the Ministry of Housing and the Ministry of Foreign Affairs, largely allocate their resources without any legislative mandate.Footnote ⁹⁴

Assessment of judicial treatment of the provision shows a gradual internalization of both the authorization to act and its restriction, but here, too, some weakening of the restrictions is evident. During its first two decades, the section was rarely relied upon and recognized only when transnational elements were involved: three decisions concerned disputes over religious sites, and one referred to section 28 as the source of the exercise of military power in the Occupied Territories, which did not rely on domestic statute-law.Footnote ⁹⁵ Courts did not rely on the provision in the context of more mundane usages of non-statutory powers, such as those discussed in the pre-Basic Law El-Saruji. This changed in the early nineties: since then, courts have relied on the provision, recognizing the breadth of areas in which non-statutory powers are invoked.Footnote ⁹⁶

Alongside the recognition of these powers, the court has developed five constraints on their exercise. First, the residuality principle, central to the law of the royal prerogative, was traced to the proviso ‘subject to any law’.Footnote ⁹⁷ Yet the impact of the residuality constraint is limited. It has aided applicants only once, and then, in conjunction with the human rights constraint, discussed below. In some cases, the statute allegedly covering the subject matter was narrowly construed, excluding the challenged action from its remit.Footnote ⁹⁸ The court has also been ready, in more than one case concerned with a statute granting benefits and subsidies, to recognize the legality of supplementary benefits and subsidies beyond statute, as well as interim benefits granted before the entry into force of the statutory arrangement. Both types of programmes were recognized as ‘parallel tracks’ available in addition to the statute-based payments.Footnote ⁹⁹ This more than echoes other systems' readiness to uphold action beyond the law as long as it does not contradict statute law.

The second limit has been read into the text of section 28, but draws on Israel's well-established judge-made ‘principle of legality’, under which action affecting a right or a liberty must be based on a statutory authority that explicitly authorizes interference with the right; general statutory delegation does not suffice.Footnote ¹⁰⁰ In Kiryat Gat, a case in which a nationwide non-statutory subsidy scheme was challenged, the court interpreted the term ‘law’ to include judge-made law, thus introducing the principle of legality in this context. In this case, the court invalidated the subsidy scheme for blatantly discriminating between Jewish and Arab settlements, in the absence of a clear statutory authorization.Footnote ¹⁰¹ Since 1992, the principle is also constitutionally embedded in two basic laws protecting human rights, under which interference with a protected right must be, inter alia, made ‘by law’ or ‘by regulation enacted by virtue of express authorisation in such law’.Footnote ¹⁰²

A third substantive constraint relies on the recently developed doctrine of ‘primary arrangements’, under which long-standing arrangements that are socially important, publicly debated, involve a high public expense, or otherwise substantially impact on the public sphere, cannot be sustained under the provision and require legislation.Footnote ¹⁰³ However, the post-decision dynamics of the two cases in which this rule was applied show weak promise: in our context, one non-statutory arrangement was replaced, after years of foot-dragging, by an open-ended empowering statute, which offers only nominal direction.Footnote ¹⁰⁴

Finally, two other constraints on the exercise of non-statutory powers limit actions to those ‘administrative’ in nature, precluding exercise of inherent judicial-type action; and public expenditure under such powers require a basis in the annual appropriation law. Neither has been central to the limitation of non-statutory powers.Footnote ¹⁰⁵

A. Divergence or Convergence?

Comparison is concerned with identifying patterns of both similarity and diversity between compared units. The convergence thesis, central to comparative law scholarship, focuses on the similar, as in Zweigert and Kötz’ claim that

Under this thesis, legal systems tend to offer functionally similar legal solutions to shared problems. The similarity is found at the law-in-action level; formal solutions are only the starting point.

A competing important group of comparatists argues that the convergence thesis is a dangerous myth that plays into the hands of politicians who wish to present so-called ‘transition States’ as partaking in the Westernisation game. Frankenberg offers a scathing critique of classical comparatists who embrace a sunny, but false, view of the globalization of constitutional law. One of his examples is the futile comparison of the regulation of abortion in China and various Western States, which is influenced by culture and politics.

Frankenberg's call for forsaking ‘[a]nalogies and presumptions of similarity’ in favour of ‘a rigorous experience of distance and difference’Footnote ¹¹⁰ is echoed in Legrand's argument that law is a cultural (that is, domestic) construct, and that the classical comparatist's ‘inherence in his (domestic) law’ renders comparison-as-harmonization impossible.Footnote ¹¹¹ Here, comparative study is not rejected, but difference is prioritized.

My analysis in Part IV offers a good example of convergence. Starting out from entirely different points of departure, three executives—a president and two prime ministers—exercise a similar non-statutory core of powers, supported, or at least tolerated by their systems. The discourses are clearly different, and some variations are evident, but the similarities are notable: despite substantial structural differences, the evolution of each of the solutions has led, to a great extent, to the convergence of a vision of an office that retains both its dominance, legal and political, but also a degree of submission to parliament and to judicial review.

First, the three examined regimes, as evolved, have never completely prohibited the invocation of non-statutory powers, despite their shared adherence to the rule of law. The core subject-matters recognized as legitimately regulable under unilateral action, or at least tolerated through the absence of judicial interdiction, are shared: emergency/national security, police, and the formation and implementation of economic policy which involves the powers of the purse. Recognition of powers in these subject matters has relied on explicit constitution-type texts, as in the case of Israel, on well-established but unwritten tenets of the constitution, as in the UK, or on open-ended interpretable constitutional provisions, as in the US. Judicial doctrines, built on the basis of texts or beyond them, have further supported the legitimacy of these powers. These include judicial recognition of inherent powers, as in early US and Israeli decisions;Footnote ¹¹² the US recognition of ‘historical gloss’;Footnote ¹¹³ creative interpretation of statutes to ensure that the challenged action escapes the residuality net, as in some Israeli cases;Footnote ¹¹⁴ and a general legitimation of action beyond statute, as opposed to action that contradicts statute.Footnote ¹¹⁵ Finally, deference doctrines and denial of review for non-justiciability have been employed to block challenges to the invocation of some similar non-statutory powers.Footnote ¹¹⁶

Moving to the evolving constraints on the exercise of non-statutory powers, here, too, similarity can be discerned. Two constraints on the exercise of non-statutory powers seem to be shared: a doctrine of diluted or tempered residuality and a rule prohibiting action in human-rights contexts. The residuality principle has remained a key feature of the British prerogative since 1688; this mainstay of the British constitution also applies to so-called ‘third source’ powers.Footnote ¹¹⁷ Residuality is also central to Israel's written arrangement,Footnote ¹¹⁸ and is the cornerstone of Youngstown, the basis for the now-established US rule that the president must rely on either the constitution or statute to invoke enforceable powers, applied inter alia in Hamdan.Footnote ¹¹⁹

Still, when intent on upholding powers despite the parallel existence of statute, the courts of these three systems have created bypasses that weaken the residuality constraint. Parallel action beyond statute is allowed virtually universally in Israel, as long as no individual rights are affected.Footnote ¹²⁰ Further, some statutes have been interpreted very broadly, to authorize action that initially did not rely on legislation, or narrowly, in order to classify the challenged action as pertaining to a different subject matter.Footnote ¹²¹ The outcome, then, is a shared commitment to the primacy of statute-law, but a far from absolute one, which is overtaken when so expedient.

The human rights constraint is only impliedly shared. Originally, only Israeli courts squarely require that an interference with rights and liberties must be authorized by a detailed, explicit statutory authorization; under this constraint, non-statutory powers affecting rights cannot be the source of such action. None of the other systems studied in this article expressly recognize this constraint; for this reason, this aspect is not discussed in detail in the respective analyses of the other two systems. Indications for the existence of such an implied constraint can be found in both systems. In the US, evidence to the contrary does exist: in Midwest Oil, the court upheld the withdrawal of access and use of lands by presidential order; in the 1980s, the ‘historical gloss’ doctrine, expressed in congressional inaction and some implied recognition, was still found sufficient to authorize the nullifying previous freezing of Iranian assets.Footnote ¹²² Yet the American system cannot be blamed for marginalizing the commitment of the system as a whole to the protection of recognized rights; since Hamdan, anti-terrorism measures are all legislated, and administrations now recognize that absent legislative or constitutional authority, the President cannot invade private rights.Footnote ¹²³

In the UK, historically recognized prerogative powers can affect the rights of individuals, as in the case of the exercise of war powers and the issuance of passports. In Entick v Carrington (1765), Lord Camden famously ruled that the Earl of Halifax's messengers held no power to search and seize personal papers in the absence of law: ‘if this is law it would be found in our books, but no such law ever existed in this country’.Footnote ¹²⁴ However, this decision, one of the mainstays of British constitutionalism, did not address prerogative powers, which were not affected by this ruling. Further, British governments were not enjoined from interfering with unrecognized rights, protected in other constitutional systems, as long as no statute prohibited such interference, as in the case of privacy, a right recognized only in 2000.Footnote ¹²⁵

This is no longer the case. Domestic law was transformed after the entry into force of the Human Rights Act 1998, which incorporated substantive parts of the European Convention of Human Right into domestic law, and now offers British courts distinct mechanisms of review of statutes when a breach of Convention rights is found.Footnote ¹²⁶

Most rights protected under the convention can be compromised if the conditions set in ‘limitation clauses’ are met. One of the conditions set in these clauses is that the interference be ‘in accordance with the law’ or ‘in conformity with the law’.Footnote ¹²⁷ These interchangeable termsFootnote ¹²⁸ could be read as requiring legislation for any breach of a protected right, but the European Court of Human Rights has advanced a different, looser interpretation. The ‘law’, under the Court's jurisprudence, must be sufficiently clear and accessible,Footnote ¹²⁹ but this does not mean that it must be primary legislation. Inter alia, the Court has recognized, in suitable cases, common-law contempt of court rules and international communications agreements.Footnote ¹³⁰ Still, some form of explicit authorization of a legal nature must be found.

Israel's additional constraint, under which primary arrangements are to be regulated under statute-law, has no equivalent in the other studied systems; applied only twice in its mother system, its actual force is challenged by the post-decision dynamics of these two affairs.Footnote ¹³¹

B. Two Further Distinctions: Functional/ Transplant-Derived Convergence in a Context-Based Framework

The juxtaposition of several solutions discussed in this article offers a pattern of convergence, but proper understanding of this convergence requires further analysis. Similarity on-the-ground can be the outcome of two parallel processes. A system may knowingly adopt a foreign legal construct, but similarity may also be the outcome of separate evolutionary processes, in the absence of trans-border influence. Advocates of transplantation obviously view the former as dominant, yet the coupling of convergence with transplantation is too easily made.

The study of legal transplants and the adoption of foreign law and legal constructs by legal systems worldwide has become one of the most influential streams of the comparative law discipline.Footnote ¹³² The early literature revolved around a controversy between ‘transferists’ and ‘culturalists’.Footnote ¹³³ Heading the ‘transferist’ camp, Alan Watson celebrated the pervasiveness of legal transplants, a universal process repeatedly occurring since Roman times, irrespective of the possible ‘fit’ between the donor and receiver.Footnote ¹³⁴ In the opposing camp, substantializing his theory of divergence, Pierre Legrand argued that transplantation is impossible, due to ingrained differences between the systems involved. A legal rule is ‘necessarily an incorporative cultural form’, and its meaning is found through essentially subjective interpretative processes, which are historically and culturally conditioned. Therefore, transplants do not occur at all: the product of moving a rule elsewhere is always something else, ‘not the same rule’.Footnote ¹³⁵

The general tone of the literature is a shared wary recognition of transplantation processes: many authors reject both the sunny aspects of Watson's world of ever-flourishing transplants and Legrand's rejection of that vision. Yet much of the general transplant literature is not contextual: it rarely distinguishes between fields or sub-fields of law.Footnote ¹³⁶

Celebrating the rise of global liberal democracy, many comparative constitutional studies focus on the judicial protection of rights under Bills of Rights. Public law comparatists usually point to the movement of the written constitution template between Western States, and from mature to new democracies, and at the global rise of judicial power and judicial review, both main elements of constitutionalism.Footnote ¹³⁷ But are these insights valid in the context of the so-called minutiae of regime structures? Can the same pattern be found in institutional-structural contexts, and, particularly, in the context of executive powers?

Research in this direction is limited. Scholars of comparative politics focus on the global diffusion of the two distinct templates—presidentialism and parliamentarism and their hybrids—paying limited attention to the wedding of these two templates;Footnote ¹³⁸ none are concerned with non-statutory powers and their transplantation. Comparative law studies of the executive branch are scarce.Footnote ¹³⁹ This article thus enters relatively uncharted territory.

Searches for evidence of transplants should focus on two stages: design and evolution through interpretation and application. Transplantation during the design stage, either with the creation of a constitution or in a subsequent amendment, occurs when its designers are positively or negatively inspired by foreign designs. Post-design interpretation (by courts) and application (by governments) further shape the contours of the framework, and may be similarly influenced. During all stages, transplantation can be overt, expressed in explanatory documents and judicial decisions, or covert, in the absence of open evidence of reliance on foreign law.Footnote ¹⁴⁰ In the context of this article, I assess the existence of transplantation by considering accessible and formal evidence; further study of the secret life of transplantations is required for a complete assessment.

I found no evidence of overt trans-border inspiration in this case study. In fact, a different pattern is evident here. The designers of the constitutional arrangements studied in this article were intent on rejecting previous domestic arrangements, considered as failed or lacking. Direct rejection of an external solution may be imputed to the Founding Fathers, committed to reject all notions monarchical. Yet even here, the US Convention's formal mandate was originally fuelled by the failure of the former domestic structure.Footnote ¹⁴¹ Israel and the UK offer different patterns, but in both, no direct external influence at the design stage is discernible. The British evolving law of the prerogative was, and remains, an innovation. As for Israel, the enaction of the Basic Law: The Government in 1968 was not part of a regime change; rather, the Basic Law aimed to codify and rationalize the law of the executive. The provision delineating executive powers was designed to fill a lacuna, which had been judicially filled in the early sixties by vague reference to ‘general government powers’.Footnote ¹⁴² Further down the constitutional history of the State, this lacuna emerged once the courts had rejected the adoption of the English prerogative; the design, then, was fuelled by an aversion to the prerogative, which had been removed from the constitutional framework.Footnote ¹⁴³

Moving to the evolution stage, explicit evidence of transplantation could have been found in domestic courts' reliance on foreign sources.Footnote ¹⁴⁴ Studies of judicial citation of foreign law have not been directly linked with the transplantation literature; many are part of the growing body of empirical research of the judiciary. Yet there is an obvious affinity between the study of citation practices and transplantation studies: the more common the citation of foreign sources, the higher the incidence of transplantation, at least on the record.

Consideration of this form of transplantation in the context of this article requires a comparison between the general citation practice in each of the studied systems and the particular pattern found in decisions concerned with non-statutory executive powers. A full appraisal of this aspect of transplantation requires sufficient quantitative-empirical data on the general systemic tendencies of foreign-source citation. Groppi and Ponthoreau's recent edited book offers a comparison of reliance on foreign precedents by the constitutional courts of 16 legal systems, distinguishing between national courts that often cite foreign precedents and those that rarely do so. In conclusion, the book offers an interesting insight: all studied constitutional courts cite foreign citations less frequently in institutional issues; judicial opinions on human-rights issues tend to be more reliant on foreign law.Footnote ¹⁴⁵

Two of the systems analysed here, those of Israel and the US, are included in Groppi and Ponthoreau's collection, but the country analyses are general and do not offer direct evidence in the context of executive powers. I build on these analyses and on the few additional quantitative studies of citation practices in these systems, by comparing the reliance patterns in the context of non-statutory powers with the limited general findings.

The question of the constitutional propriety of citing foreign sources has been hotly debated in the United States,Footnote ¹⁴⁶ but I am less concerned here with the normative aspects of this practice. US-centred empirical studies of judicial citation practices that have isolated foreign sources from domestic ones reach one conclusion: citation of foreign jurisprudence in US courts is negligible.Footnote ¹⁴⁷ Only two of the key Supreme Court decisions on presidential unilateral power cite foreign sources; in both, the contexts have no bearing on the legitimacy or source of non-statutory powers.Footnote ¹⁴⁸

The general citation practices in Israel are materially different. Two large-scale quantitative studies of thousands of Supreme Court decisions show a relatively high reliance on foreign precedents.Footnote ¹⁴⁹ Against this pattern, eight of the thirteen Israeli decisions cited in this article that address the invocation of non-statutory government powers contain citations of foreign sources, but with the exception of one case, none of these foreign precedents are concerned at all with the source, legitimacy or nature of such powers. In Kiryat-Gat, Justice Goldberg curtly cited Youngstown to support his argument for the application of the residuality principle.Footnote ¹⁵⁰ In all other decisions, citations support a variety of issues, from police powers to the political questions doctrine. Some of these decisions are laden with references to foreign jurisprudence; the silence in the context of the legitimacy of the Israeli solution is especially telling.Footnote ¹⁵¹

British large-scale quantitative study of citation practices is still lacking. In an admittedly small sample of cases concerned with the right to liberty and fair trial in the context of anti-terrorism measures, Ian Cram finds a recurring pattern of reliance on foreign sources. This indication of citation practices in a distinct human-rights context is currently the best available comparator.Footnote ¹⁵² By comparison, citation of foreign sources in key non-statutory powers decisions is limited: three of the nine decisions cited in this article contain references to foreign case-law, but once again, none of these sources are concerned with the source and nature of the challenged executive power.Footnote ¹⁵³

As a final test of the extent of reliance on foreign precedents this field, I consider the number of times key US and UK non-statutory powers decisions were cited in the examined systems without limiting the search to decisions directly concerned with non-statutory powers.Footnote ¹⁵⁴ No Federal US court has ever cited any of the key decisions delivered in the other systems.Footnote ¹⁵⁵ British courts cited Dames & Moore in one decision and Hamdan in five, but all references are part of the factual background and are not linked with the judicial reasoning over challenges to domestic government action.Footnote ¹⁵⁶De Keyser was cited six times by the Supreme Court of Israel, but only in the context of the law of confiscation.Footnote ¹⁵⁷ The Israeli Supreme Court cited GCHQ in two decisions, and Youngstown in four; only one citation was used to support the court's ruling on the proper extent of non-statutory executive powers.Footnote ¹⁵⁸

It would seem, then, that in the constitutional systems analysed in this article, the design and evolution of the distinct solutions to this shared problem show virtually no evidence of overt transplantation. Whether these findings reflect a global pattern, which challenges the discourse of world constitutionalism at least in structural-institutional contexts, requires further comparative study.

C. Assessing Functional Convergence

How can convergence, arrived at in the virtual absence of cross-border transplantation be explained in this case, and beyond? ‘Ancestor’ systems may have created their respective solutions independently, but should the dearth of explicit evidence of external influence during their evolution stages be imputed to their ‘ancestor’ status? Why do Israeli courts, operating in a non-ancestor system, show a similar marginalization of foreign law in this context, contrary to their general tendency to extensively rely on foreign sources in other constitutional matters?

The relative similarity of the contours of non-statutory executive powers in the three Western systems can be tentatively explained by their shared democratic ethos and the generally similar socio-economic climates. At the meta-level of the nature of these polities as democratic States, convergence can well be described as transplant-derived. The adherence to the rule of law, the primacy of individual liberty, and the establishment of some form of separation of powers have migrated from the ancestor democracies, England and the US, to Israel, among many nations. This shared, if vague, ethos has shaped public law in all democracies. Those countries also share, on a same general level, social and political realities that directly impact on the extent of executive powers. The separation of powers ideal infers subjection of the executive branch to statute, but the delineation of the powers of central government rests on an ingrained tension between the need to grant power to the government and the dangers of abuse of the granted power. Thus, strong forces supporting the enhancement of power, briefly addressed in Part II, compete with legality arguments, and have promoted the adoption, formal or de facto, of doctrines that uphold some of these powers, or at least doctrines of deference and non-intervention. Eventually, non-statutory powers are likely to be invoked in contexts that render them socially or politically expedient. But why is transnational transplantation missing in this institutional aspect of constitutional law?

Groppi and Pontoreau's distinction between overt reliance on foreign sources in human-rights and in institutional issues is an important starting point. The editors of this collection offer two explanations for the relative prevalence of foreign citation in human-rights contexts. First, similarities of constitutional bills of rights, which indicate transplantation at the design stage, enhance the tendency to consider foreign systems. This reason links with the second explanation, which I find stronger. The protection of human rights by law is essentially universal: Human rights treaties and other rules of international humanitarian law apply across borders as well as domestically.Footnote ¹⁵⁹

Yet Groppi and Ponthoreau do not explain the lower incidence of visible cross-border influence in institutional-structural elements. Some of the reasons for the emergence of this pattern may be gleaned from general arguments that resist convergence in constitutional law, succinctly framed, but not followed as a call for rejection of comparison, by Professor Saunders:

This argument is strongest in the context of structural-institutional matters that pertain to the sovereignty of the nation, as in the case of executive powers. Courts deciding in such areas do not only settle disagreements that have reached the court; their output signals the unity of the State and its uniqueness as a separate and independent structural entity. I argue that the closer the issue set before constitution designers and courts to the core structural elements of the constitution, as in the issue studied in this article, the structure of executive power, the more likely the absence of development of domestic law by relying on other systems, unless strong external political pressure unsettles internal evolution. Development of this argument and assessment of its force in new democracies are relegated to further research.