Software behemoth Microsoft has put its weight behind Washington state’s proposed equal marriage laws.

The corporation joined a variety of other employers, including Nike, to build on its “history of supporting corporate and public policies that promote inclusion and equality” by supporting the proposal to extend marriage rights to gay couples.

Microsoft, which has its headquarters in the Washington city of Redmond, also backed the state’s successful 2009 legislation to give gay couple’s domestic partnerships the same rights as marriages.

In a statement yesterday, it said: “Microsoft’s greatest asset is a talented workforce as diverse as our customers. As other states recognize marriage equality, Washington’s employers are at a disadvantage if we cannot offer a similar, equitable and inclusive environment to our talented employees, our top recruits and their families.

“This legislation would put Washington employers on equal footing with employers in the six other states that already recognize the committed relationships of same-sex couples.

“Passing the bill would be good for our business and for the state’s economy.”

Brad Smith, the corporation’s General Counsel & Executive Vice President, Legal & Corporate Affairs, said the rationale was that a diverse and inclusive workforce can better “understand and connect” with customers.

He wrote on his blog: “While some of our employees literally grew up around the corner, others have come from every state and almost 150 countries around the world.

“They reflect virtually every background in the country and on the planet. They bring their creativity to work, and they put it to good use in developing new products and serving our customers. There simply is no substitute for their diverse backgrounds, perspectives, skills and experiences.

“Inclusiveness is therefore a fundamental part of our values, and is integral to the company’s business success.

“This means it’s important to go beyond simply forbidding discrimination; we strive to actively promote diversity, equality and inclusion in our workplace.”

Earlier this week, the bishops of Washington state urged opposition to marriage equality proposals to protect the “unique sacrifices” made by straight couples who marry and have children.

In 2009, Microsoft made a $100,000 (£62,976) donation to campaigners in Washington before the ballot which gave gay couples broader rights under domestic partnerships law.

The law, known as the ‘Everything but marriage’ measure, was has been put on hold due to the referendum campaign, known as R-71.

Microsoft, which is based in Redmond, made the donation to Washington Families Standing Together. It is thought to be the single largest donation in favour of the pro-gay campaign.