King & Spalding, the legal firm hired to represent the DOMA (Defense of Marriage Act), quit after the Human Rights Campaign, a gay rights group, launched a campaign against it. There are three issues here that should be examined.
Working backwards, it was wrong of King & Spalding to back out of representing the act and it was wrong of the Human Rights Campaign to pressure King & Spalding. This establishes a bad president that may be used in the future on both sides. Trying to assure that an unpopular law is not given competent representation in a legal challenge eats away at our entire legal system.
What of the DOMA itself? Basically it says that states do not have to recognize same-sex or polygamous marriages from other states. It does not stop any state from legalizing same-sex marriage. Dahlia Lithwick in Slate dismisses the act as a GOP Hatefest but it was passed in 1996 by a large bipartisan majority (85–14 in the Senate and a 342–67) and quickly signed into law by President Clinton. Clinton himself said at the time, "I remain opposed to same-sex marriage. I believe marriage is an institution for the union of a man and a woman. This has been my long-standing position, and it is not being reviewed or reconsidered."
Regardless of your opinion on same-sex marriage, the law was a good thing. At the time, court challenges had legalized same-sex marriage in a couple of states and gay advocates were hoping to use this to force nation-wide legalization of gay marriage. This would have been a disaster. It would have meant that a handful of state judges had redefined marriage on a national level. Consider how disruptive it was when the Supreme Court legalized abortion. That battle is still being re-fought. Every candidate for the court is carefully scrutinized against a future challenge to Roe v. Wade. The nation does not need another ongoing conflict like that.
In fact, the whole battle over gay marriage has been waged poorly since the late 1990s. In the mid-90s the idea of civil partnerships was gaining favor. It is hard to argue with the basic fairness of partnerships. The problem was that the more radical element in the gay advocacy groups decided that civil partnerships were insufficient. They demanded an all or nothing approach. That led directly to the DOMA. Fifteen years later they are still engaged in an all or nothing battle with little to show for it. If they had accepted an incremental approach they probably would have achieved their goals by now. Great Britain took that approach and fully legalized same-sex marriage last year. By going with the confrontational approach the gay rights advocates set their cause back a decade and a half and counting.