This week the Supreme Court of the United States overturned the Defense of Marriage Act. The case being heard was brought by a woman named Edith Windsor. She was forced to pay Estate Taxes when her wife died and so she sued the IRS to get a refund. The reason the IRS could not allow her the standard marital exemption from Estate Taxes is because DOMA, the Defense of Marriage Act, defined marriage as between a man and woman when it came to Federal benefits. Tax exemptions are Federal benefits and therefore IRS was required to deny that tax exemption even though she was legally married. The Supreme Court ruled that DOMA violated the Equal Protection clause and demeaned gay, married people.
Normally, you see Republicans in favor of anything that fights the Estate Tax.
Normally, you see Republicans in favor of anything that attacks the IRS.
If Edith was a guy or if her wife, Thea, was a guy, then most Republicans would have been wholeheartedly in favor of this lawsuit... but when it's two women? No, no way.