Game companies Electronic Arts, Microsoft, and Zynga have joined numerous other parties in a formal amicus brief that opposes the United States' Defense of Marriage Act, which defines marriage as the legal union between one man and one woman, and stands as one of the largest obstacles against gay marriage in the country.The companies say the Defense of Marriage act is discriminatory, hurts morale, and even creates some uncomfortable tax issues within their organizations. The parties in the brief, which also include Viacom, Starbucks and the cities of New York and San Francisco, among others, are urging the U.S.'s Ninth Circuit Court of Appeals to find portions of the Act unconstitutional.The brief itself was filed in the case of Karen Golinski v. the US Office of Personnel Management, which is examining the validity of the contentious U.S. law. If the case goes all the way to the Supreme Court, it could become the ultimate test of the legislation's contitutionality.Even outside this brief, companies like EA have been particularly outspoken about their support for LGBT employees of late. For instance, EA openly participated in the San Francisco and Seattle Pride events this year, and took part in the extremely popular "It Gets Better" campaign.