The National Secretary of the Australian Workers’ Union, Paul Howes, says he wants Labor MPs to be forced to vote in favour of equal marriage, in line with the party’s platform.

Currently, Labor MPs would be allowed a conscience vote on the issue.

But Mr Howes says it is no longer appropriate for a progressive political party to allow its MPs to vote against equal marriage laws.

“The Australian Labor Party’s current position and my view at Labor’s last National Conference on marriage equality is wrong.

“By designating marriage equality as a conscience vote issue, we have allowed ourselves to make a basic category error; one which I believe fundamentally grates with what it is that the Labor Party stands for.”

He adds: “Conscience votes should be reserved for those very rare issues of individual moral judgement, in which the issue at hand simply defies objective boundaries.

“Conceptions of when human life begins and the conditions under which it should be extinguished can fit this definition.

“Marriage equality, on the other hand, does not even come close. It is not an issue of individual conscience; it is a matter of basic social justice.”

The party lost power in September’s federal election. Former Labor leader and Prime Minister Kevin Rudd, who supports equal marriage, lost out to conservative challenger Tony Abbott, who opposes marriage rights for same-sex couples.

Efforts to legalise the measure failed in the Australian Parliament in September 2012.