TO CHEERS from gay-rights activists, Barack Obama has finally accepted that their fight belongs in the pantheon of American civil-rights struggles. Many employers have found a more prosaic reason to lend their backing to same-sex marriage: dealing with discriminatory laws is an administrative drag.

Section 3 of the Defence of Marriage Act (DOMA), signed by Bill Clinton in 1996, says that for federal purposes only heterosexual unions count as marriage. This bars gay couples from over 1,100 federal benefits, such as inheritance-tax relief or the right to file joint tax returns. But two appeals courts have struck down section 3, and on March 27th the case reaches the Supreme Court. Last week 278 employers, including Deutsche Bank and Microsoft, signed an “amicus” brief urging the nine justices to scrap the law.

The problem is that nine states (plus Washington, DC) allow gay marriage, and three others recognise gay unions solemnised elsewhere. This conflict between federal and state law creates all sorts of headaches, such as separate payroll systems and differing tax treatment of health-care benefits. “Even sophisticated employers struggle,” the brief says.

Employees suffer, too. Hard data are scarce, but a 2007 study found that under DOMA the average married gay worker paid over $1,000 more a year in taxes than a married straight worker receiving the same workplace benefits. Many firms find ways to get around such inequities. But these are complex and costly.

The links between marriage laws and workplace benefits have long pushed some employers into the battle for gay rights. “They felt convinced that changes would help them retain employees,” observes M.V. Lee Badgett, an economist at the University of Massachusetts Amherst. This, she says, is particularly true in America, where the employer tends to be responsible for health insurance. And, she could have added, where the tax code is ridiculously complicated.

A second gay-marriage case facing the Supreme Court has brought out a different set of arguments. One hundred employers have signed another amicus brief calling on the court to strike down Proposition 8, a Californian ban on gay marriage. That case reaches the justices on March 26th.

Prop 8 presents Californian firms with few direct burdens. But, the brief argues, “it impedes businesses from achieving the market’s ideal of efficient operations” by placing them at a disadvantage when it comes to recruitment and by damaging the morale of gay employees. Similar arguments have been made by around 50 business signatories to an open letter urging the Illinois legislature to allow same-sex marriage, and by the Seattle Chamber of Commerce during a campaign in Washington state last year.

The moral case for gay marriage does not depend on the fact that it reduces red tape. But every voice helps, even that of corporate America.