Same-sex marriage has been a contentious political issue in the United States, with opposition to it frequently articulated on religious grounds. More specifically, the rights of lesbians and gay men seem to be pitted against the rights of religious individuals. Emily Gill's book is a welcome and persuasive attempt to move beyond this apparent stalemate between contending rights. Combining liberal theory and public law, as well as lesbian and gay studies, Gill argues that the First Amendment's establishment and free-exercise clauses call for the legalization of same-sex marriage. The current restriction of marriage to opposite-sex couples amounts to an unconstitutional establishment of religion—namely, heterosexuality—and furthermore restricts the free-exercise rights of lesbians and gay men. Only by legalizing same-sex marriage would the liberal state follow through on its commitment to remain neutral among various religious and nonreligious orientations. In other words, to push for same-sex marriage is a religious claim, not one that runs counter to religious freedoms, and therefore should meet with the same protections as other religious rights claims.

It would be fair to characterize Gill's book as divided in half: The first three chapters prepare some of the theoretical grounds for the subsequent reinterpretation of the establishment and free-exercise clauses (Chapters 4 through 6). For example, Chapter 2 contains a compelling consideration of the liberal effort to practice neutrality among rival religious or ethical orientations. Gill demonstrates that liberal neutrality cannot be absolute (p. 47), and that the liberal state thus must aspire to “civic equality [which] not only may require a qualified noninterference with belief or identity and practice, but also may require public action that may prevent the creation of two classes of citizens” (p. 48). Chapter 3 follows logically, as the author here presents how same-sex marriage registers in a starkly different ethical light to its traditionalist or feminist/queer opponents, as well as its traditionalist or liberal supporters. While she herself falls into the latter camp, her fairness in describing each of these voices on its own terms is impressive—even as she still offers disarming critiques, especially of traditionalist opponents' “sectarian” logic and limited understanding of human complementarity (pp. 68–70). Chapter 3 thus drives home the point that the liberal state cannot take a position on same-sex marriage that pleases all sides. On the contrary, it will have to embrace a form of liberal non-neutrality regarding same-sex marriage within which the state then practices liberal neutrality (pp. 43–44).

In Chapter 4, Gill draws on Supreme Court rulings on the establishment clause—on Justice Sandra Day O'Connor's endorsement test (pp. 113–24) and Justice Anthony Kennedy's coercion test (pp. 124–33)—to make her case for same-sex marriage. The two sections are somewhat dissimilar in that the author considers both controlling and dissenting opinions for the endorsement test. Ironically, while she identifies with the endorsement test, and only turns to the coercion test as a backup (p. 125), her presentation of the latter is thus clearer than that of the former. Confoundingly, she establishes support for same-sex marriage from both the prevailing and dissenting legal interpretations of the endorsement test. Applying O'Connor's definition that the state may not treat some as insiders and others as outsiders to the question of same-sex marriage makes sense (p. 115).

Gill also employs a dissent by Justice Antonin Scalia, however: “If Scalia believes that religion may be favored as an institution as long as we do not prefer one religion over another, marriage might logically be favored as an institution as long as we allow diversity among the types of couples who may marry” (p. 123). Why would she take Scalia at his word that he favors religious diversity in seeking to uphold a display of the Ten Commandments in courthouses? Given her earlier discussion of neutrality depending on context, Gill should understand that this in reality favors the majority religion. More importantly, she later notes how Scalia worries about the possible legalization of same-sex marriage in his dissent to Lawrence v. Texas (p. 176), which clearly means that he would not at all make the analogical jump from religious freedom to the freedom to marry. Gill could have perhaps presented a case for a counterintuitive consequence of analogical thinking; absent such justification, an impression remains of her argument stretching the analogy too far. Such problems could have been avoided, and the section on the endorsement test strengthened, by focusing on O'Connor's and complementary rulings.

Gill's free-exercise argument in Chapter 5 rests on three pillars: Martha Nussbaum's and Andrew Murphy's understanding of conscientious belief, and her own interpretation of select Supreme Court opinions on the free exercise of religion. For Gill's argument, it is critical not to restrict conscientious belief to “what we think of as conventionally religious values”; furthermore, we should not mistakenly assume “that only religion as conventionally understood is special” (p. 157). Justice John Harlan broadens free exercise along these lines when he deems “purely moral, ethical and philosophical sources” as comparable to religious ones in justifying conscientious objection (p. 197). Gill links these familiar, if broadened, conceptions of free exercise with the idea that both religion and sexuality are “forms of intimate self-expression” (p. 164) and that same-sex couples are driven by “the truth that only life with another particular person will fulfill life's ultimate meaning” (p. 168). That same-sex marriage is only a “benign variation” of marriage (p. 169) not only warrants its legalization but furthermore shows how the author is sensitive to refraining from going too far with the redefinition of protected conscientious belief.

Surprising for an argument that develops an analogy to religion is Gill's statement early in her book “that the analogy between antimiscegenation laws and the same-sex marriage ban is appropriate” (p. 21). Moreover, she in fact relies on the antimiscegenation analogy as part of her argument for showing that current marriage law creates unjust hierarchy: “[T]he same-sex marriage ban maintains a caste system that privileges heterosexuality over nonheterosexuality” (p. 21; see also pp. 24 and 81). If, however, the antimiscegenation analogy already justifies same-sex marriage, why then pursue a contentious analogy between sexual identity and faith? At the least, it would have been helpful for Gill to clarify the relative strengths and weaknesses of both the antimiscegenation and the religion analogies to explain trade-offs of respective approaches. Better yet, the author should have delineated why specifically she does not pursue an analogy she otherwise accepts. I surmise that this might have to do with the question of essentialism, which an analogy to race might raise more forcefully (p. 22). In particular, protection of religion does not depend on claims to biological essence; instead, religious identities are simultaneously experienced as involuntary and voluntary—and protected regardless (pp. 165–66).

In a way, Gill is too modest here about the merits and advantage of her argument: It has the potential to redefine our understanding of what is at stake in arguing for lesbian, gay, bisexual, and transgender rights and same-sex marriage.