President Obama backs nationwide gay marriage, says state bans are 'unconstitutional'

The administration filed a brief at the US Supreme Court backing homosexual couples challenging laws in four states

Married same-sex couples will now enjoy similar rights to heterosexual couple following a new announcement from the Obama administration (Getty Images)

The White House has officially backed a proposal to scrap state bans on gay marriage, claiming such laws are "incompatible with the Constitution".

In what represents its first formal involvement in the US Supreme Court's deliberations on nationwide same-sex marriage, the Obama administration filed a brief relating to rulings in Kentucky, Michigan, Ohio and Tennesse. Beyond these four states, gay marriage is legal to proceed in 36 states, banned in 7 states, and in Alabama, Kansas and Missouri the legal situation is a bit more complicated.

Referring to anti-gay marriage rulings at the state level, Solicitor General Donald Verrilli wrote: "These facially discriminatory laws impose concrete harms on same-sex couples and send the inescapable message that same-sex couples and their children are second-class families, unworthy of the recognition and benefits that opposite-sex couples take for granted."

This was one of a number of briefs backing gay marriage that were filed ahead of Friday's deadline, including one signed by major companies including Google, American Airlines, Goldman Sachs and Johnson & Johnson.

On the other side, a brief was filed on behalf of conservative activists led by former former Republican National Committee Chairman Ken Mehlman and David Koch, one of the politically powerful billionaire Koch brothers.

The deadline for gay-marriage opposition briefs isn't until later this month.

The court will hear oral arguments on April 28.