The reputation of canon law has never been lower. As the abuse crisis deepens, canon law is perceived as the instrument of a hierarchy blindly promoting its own interests and protecting its members, impervious to the suffering of individuals. The Roman Catholic Church's law is viewed as a tool and symptom of its determination to preserve power and ignore modern life. Judith Hahn's book does not deal specifically with the abuse crisis, but concerns itself with underlying problems laid bare by that crisis: how is the Church to legislate and apply universal canonical norms in a way that is sensitive to modern cultural realities? Canon law faces its own crisis, as the universal norms it upholds appear irrelevant or harmful to local communities. Natural law, the grounding of the Catholic Church's teaching in divinely revealed truths embedded in creation, has little traction outside ecclesiastical circles, and fails to convince those whose personal experience resists the impersonal and hierarchical character of the Church's law.

This book, wisely, does not engage in a head-on battle with canon law and its legislators, but provides a thoughtful and helpful analysis of the current dire situation, and a comprehensive series of suggestions for its remedy. Hahn begins by affirming the existence and value of natural law – but with important qualifications. While there may be no argument about the existence of normative realities, the consequences of these fundamental goods – or how, or by whom, they can be perceived – are far from clear. The result is a rupture between universal law and the lived reality of members of the Roman Catholic Church: a real ‘culture war’ in which universal norms are opposed to local realities.

The second part of the book suggests solutions to this crisis. While many would simply reject natural law as a useful category, or would seek to remodel canon law along the lines of secular law codes, Hahn's quest is to render canon law fit for purpose, in a way that will win approval from and adherence by the faithful. That means, in the first place, making the law relevant to the lives of those it claims to govern, and reshaping it to accommodate the modern realities of Catholic Church life. To strengthen her case, Hahn points out some current anomalies: canon law demands freedom of theological research, while in practice severely limiting the right of researchers to dissent from Church teaching. While advocating equal rights for all members of the Church, the law accords different rights to laity and to women. The key issue, however, is that the revision and application of canon law is reserved to a hierarchical minority, which perpetuates an outdated model of ‘command and obedience’. Church hierarchy, oblivious to cultural diversity and modern lived reality, does not command the respect of the faithful – a situation which threatens the existence of canon law itself.

Historically, the Roman Catholic Church has been afraid that diversity is a threat to unity. Centralising the legal system, even so far as its language, provides the certainty that is essential if the visible Church is authentically to equip its members for salvation. Yet Lumen Gentium did go some way to balance the demands of universality and diversity, especially in the way that it associated those outside the visible Church with its saving activity. Herein is a model for the methodology and ecclesiology of canon law, so that it may more effectively present an image of the Church of God. For Hahn, the process of revision or creation of laws must be broadened, truly to represent those to whom the law will be applied (notably laity and especially women). Rather than ignoring local experience, canon law should embrace diverse local customs (for this reason, Hahn prefers the term ‘global law’ to ‘universal law’), employing the techniques of subsidiarity and consensus to engage the faithful, making its legislative procedure more transparent and replacing sanction with persuasion and explanation.

It is impossible for a non-canonist such as this reviewer not to see here another aspect of the debate raging throughout the Catholic Church on the relationship between central and local authority. Hahn acknowledges an ecclesiological aspect to her quest, and she might have backed this up with more reference to the programme of Pope Francis; the synodical model she proposes has no keener advocate than the Pope himself. Ecumenism offers strong parallels to what Hahn is seeking. While she cites telling examples from Judaism and Islam, the Catholic Church's engagement with other Christian communities which model authority in different ways would be equally illuminating. The most recent statement from the Anglican–Roman Catholic dialogue, indeed, treads similar territory as it answers the mandate to explore ‘Church as communion – local and universal’. Moreover, many of the problems facing modern ecumenical dialogue – how to make its pronouncements relevant in particular settings, and how to allow the lived experience of those in local communities to have a bearing on the universal structure – are reminiscent of those outlined in this book in the context of canon law.

Going further, many of Hahn's proposals are already realities in the structures of other ecclesial bodies. Anglicanism has taken great pains to employ ‘legal flexibility’ in its ecclesial life, and its strategies for dealing with local dissent or objection in a positive and charitable way sound similar to solutions proposed by Hahn. But therein is the rub. Persuasive argument, synodical decision-making and constructive interplay have in practice resulted in theological impasse, loss of ecclesial integrity and the reality of institutionalised schism.

This book reminds us that canon law does not stand in the Catholic Church as an isolated reality, but embodies, and relates to, its ecclesiology and theology. In particular, the potential of canon law to provide a fresh angle on the ecumenical and inter-faith agenda is made clear, together with the value of natural law in establishing new forms of consensus. But, employing Hahn's own call to realism about local realities, it is hard to be as optimistic that the remodelling of canon law along more diverse lines will provide a ready solution to the Church's problems.