Country after country in the western world has moved to legalise same-sex marriage, leaving our liberal democracy in danger of being exposed as intolerant and bigoted.

There is of course no need for a referendum in Australia to decide the issue because we do not face the same constitutional hurdle that the once socially conservative Ireland faced. 

In Australia an act of Parliament would suffice and in the right circumstances would be much easier to pass than a referendum.

Those circumstances are simply that MPs across all parties should be free to exercise a conscience vote.

Some in the Labor Party have argued that since it is not a life and death issue a party policy in favour of same-sex marriage should replace a conscience vote. Under that scenario all Labor MPs would be obliged to vote for it.

On the Coalition side there is a reluctance to move away from a party position against same-sex marriage to allowing MPs a conscience vote.

While a referendum which passed same-sex marriage would provide the most emphatic endorsement of the right of gay couples to marry, the majority of voters and majority of states formula would make a yes vote extremely difficult to get.

So difficult in fact that a successful referendum vote could lag decades behind the majority of public opinion.

The comments of MP for Calare, John Cobb, illuminate one of the objections many heterosexual voters have. Mr Cobb says he would support a same-sex union, as long as it is not called a marriage.

His reasoning is that the term “union” does not undermine the value or sanctity of the heterosexual union called “marriage”.

But why should it? Gay couples want the right to be married as much for the public statement this makes about their commitment to each other as for the legal status it confers.

This is just one of the same-sex marriage issues our parliamentarians should be debating and voting on, in good conscience.