Several large corporations signed on to an amicus brief in the landmark Hollingsworth v. Perry case, which is now in front of the Supreme Court and which could strike down laws banning same-sex marriages, like California's ballot initiative Proposition 8, as unconstitutional.
According to a draft copy obtained by Fortune, the companies argue that such laws "send an unmistakeable signal that same-sex couples are in some way inferior to opposite-sex couples, a proposition that is anathema to amici's commitment to equality and fair treatment to all."
Fortune's Roger Parloff reports that at least 60 companies had committed to signing the brief as of Tuesday and that number is expected to rise today. Intel, Morgan Stanley, Apple, Facebook and eBay are among today's newest signatories. Among the companies that signed on to the brief earlier are Kimpton, Levi Strauss, McGraw Hill, Nike, Office Depot, and Verizon.
The brief, which challenges Prop. 8, also argues, writes Parloff, that "recognizing the rights of same-sex couples to marry is more than a constitutional issue. It is a business imperative."
The underlying argument states that "By singling out a group for less favorable treatment, Proposition 8 impedes businesses from achieving the market's ideal of efficient operations — particularly in recruiting, hiring, and retaining talented people who are in the best position to operate at their highest capacity. Amici are competing domestically and internationally with companies inside and outside the United States in places where all couples, regardless of whether they are of the same sex, are afforded equal access to marriage."
Parloff also writes that the brief argues that when "potential recruits or employees are members of a same-sex couple," they "may forgo the opportunity to work in California, and prefer other states (like Iowa, New York, and Massachusetts) or other nations (like Spain, Sweden, Denmark, the Netherlands, Portugal, or Belgium) where they can be married and obtain equal treatment and respect under the law."
Go to Fortune for the full report.