Electronic Arts, Microsoft, and Zynga have thrown their lots in with dozens of other businesses in opposition to the Defense of Marriage Act. The companies signed a joint amicus brief, an official filing on behalf of parties interested in but not directly involved in a case, outlining their objections for the benefit of the United States Ninth Circuit Court of Appeals. (Disclosure: GameSpot's parent company CBS also signed the brief.)
The Defense of Marriage Act, which was enacted by the federal government in 1996, legally defines marriage as between one man and one woman. The Obama administration since found the act's third section (which contains the definition) unconstitutional, and has refused to act upon it.
The brief states that being subject to both state recognition of same-sex marriage and the federal Defense of Marriage Act "puts us, as employers and enterprises, to unnecessary cost and administrative complexity, and regardless of our business or professional judgment forces us to discriminate against a class of our lawfully-married employees, upon whose welfare and morale our own success in part depends."
The Ninth Circuit Court of Appeals is currently hearing the case of Karen Golinski v. the US Office of Personnel Management. Golinski won the right for her federal employee health coverage to extend to her wife when a district court found parts of the Defense of Marriage Act unconstitutional, but the case was appealed by the Republican-led Bipartisan Legal Advisory Group.