Married same-sex couples are suing the federal government, claiming the act discriminates against gay couples and is unconstitutional because it denies them access to federal benefits. Mary Ritchie, a Massachusetts State Police trooper, has been married for almost five years and has two children. But when she files her federal income tax return, she's not allowed to check the "married filing jointly" box. That's because Ritchie and her spouse, Kathleen Bush, are a gay couple, and the federal Defense of Marriage Act makes them ineligible to file joint tax returns. Now Ritchie, Bush and more than a dozen others are...