The American state of New Jersey has become the fifth state in the nation to grant marriage rights to same-sex couples.

A new law, which was enforced across the state today, allows gay and lesbian couples to apply for a civil union and benefit from the same legal protection that heterosexual couples enjoy.

However, the new unions are not identified as a marriage.

The legislation follows a state Supreme Court ruling in October last year which held that same-sex couples should be entitled to all of the state’s 850 marital rights, reports by NorthJersey.com

Ed Barocas, legal director of the American Civil Liberties Union of New Jersey, welcomed the legislation.

“As New Jersey’s Civil Unions Law takes effect, same-sex couples and their families throughout the state will be afforded numerous rights and responsibilities that the State of New Jersey has previously denied them.

“In that way, it is a wonderful moment and a step toward equality,” he said.

But he warned that failing to recognise the legal unions as marriage opened the door for discrimination.

“[the legislation] also marks a sad and unfulfilling moment in the history of our state, as it is the day in which we officially institutionalise discrimination,” he said.

“Giving a historically rights-deprived group of citizens, at long last, the rights of enjoyed by all others, but then labelling them differently from that of the majority, is a state-sanctioned act of setting certain classes of citizens legally apart.”

In addition to allowing New Jersey citizens to apply for a civil union, the state must also legally recognise gay couples who have been married or joined in civil unions outside the state or overseas.

Currently Massachusetts is the only US state to marry same-sex couples but civil unions are legal in Vermont and Connecticut.

Couples who have already been joined under civil union can also have their partnership reaffirmed in New Jersey and waive the 72-hour wait that applicants for civil unions currently face.

Steven Goldstein, chairman of New Jersey’s Garden State Equality, a gay-rights group, did just that in the early hours of Monday with his partner Daniel Cross.

In doing so the couple became the first same-sex couple to be granted the state’s legal rights of marriage, reports.

The couple admitted that they weren’t yet satisfied with the law.

“Nothing short of marriage will do,” Gross told NorthJersey.com

New Jersey considered to be one of the most liberal states in the America.

It decriminalised consensual gay sex in 1979 and in 1991 anti-discrimination legislation was amended to include sexual orientation a basis for which discrimination is prohibited in areas such as employment, housing and credit.