Legendary actor Clint Eastwood has voiced his support for same-sex marriage after signing a legal brief challenging a ban on gay unions across America.

The Dirty Harry star, a longtime Republican who publicly backed his party's top choice, Mitt Romney, in last year's (12) U.S. presidential elections, has gone against conservative beliefs and given his approval to a campaign aiming to overturn the controversial Proposition 8 ruling, which outlaws same-sex marriage in California, and challenge the federal Defense of Marriage Act.

The amicus 'friend of the court' brief, drafted by officials at the American Foundation for Equal Rights (Afer), has been submitted to the U.S. Supreme Court in the hope of clearing the way for same-sex couples to legally wed across the country - and Eastwood's is among the signatures on the document, according to political blog Breitart.com.

The brief states that gay marriage is actually in line with the Republican Party supporters' strong beliefs in family values, limited government and individual freedom.

Gay unions were made legal for the first time in California in 2008 but Proposition 8 outlawed them just six months later. The controversial ruling was reviewed in a federal appeals court and declared unconstitutional in a landmark decision last year (Feb12).

Eastwood's inclusion in the petition isn't his first step into politics - he infamously engaged in a conversation with an empty chair while giving a speech at the Republican National Convention last year (12).