The 278 employers signed on to a friend-of-the-court brief in advance of argument in the high court, United States vs. Windsor, March 27.
The brief says, "DOMA forces [the businesses] to administer dual systems of benefits and payroll, and imposes on them the cost of the workarounds necessary to protect married colleagues," the Los Angeles Times reported.
The report said in those states that allow gay marriage, companies must treat employees with same-sex spouses as single for federal tax withholding and benefits, and many employers keep two sets of books -- one for state and one for federal purposes.
In the DOMA case, only section 3 of the act is challenged. Section 3 says, "In determining the meaning of any act of Congress, or of any ruling, regulation, or interpretation of the various administrative bureaus and agencies of the United States, the word 'marriage' means only a legal union between one man and one woman as husband and wife, and the word 'spouse' refers only to a person of the opposite sex who is a husband or a wife."
The challenge was brought by Edith Windsor, now 83, who had married her same-sex partner of 40 years in Canada in 2007. When her partner died in 2009 of multiple sclerosis, she left her estate to Windsor.
As executor of the estate, Windsor paid approximately $363,000 in federal estate taxes, but filed a refund claim under a federal statute that says "property that passes from a decedent to a surviving spouse may generally pass free of federal estate taxes." The Internal Revenue Service denied the claim because Windsor is not a "spouse" under DOMA's Section 3 and thus not a "surviving spouse" within the meaning of the federal estate tax statute.
The Obama administration has gone from refusing to defend DOMA to actively challenging it as unconstitutional.
Since the Obama administration won't defend the act, the Bipartisan Legal Advisory Group of the U.S. House of Representatives, or BLAG, has taken up the banner. BLAG represents the GOP leadership, including House Speaker John Boehner, R-Ohio.
Notable deaths of 2014 [PHOTOS]