Wendy Kaminer, who supports marriage equality, chides the ACLU:
Not surprisingly, the right wing, anti-gay Alliance Defense Fund is perhaps the primary defender of First Amendment rights in cases involving the anti-gay speech and belief of conservative Christians. ADF receives (and perhaps desires) little assistance from the ACLU, an increasingly unreliable defender of speech and belief that conflict with its gay rights agenda: while the ACLU aggressively defended the rights of students to wear t-shirts to school celebrating gay rights, for example, it stayed out of an important federal case, Harper v Poway, involving a Christian student punished for wearing an anti-gay t-shirt, even when the case reached the Supreme Court. National and state spokespeople for the ACLU, once a staunch defender of freedom of conscience, have pointedly ignored an invitation to comment on Julea Ward's federal case, although they might simply have pointed out that liberty cannot be secured for some without securing it for all.
Title from Anthony Lewis' excellent biography of the first amendment. My own defense of this position here.