The Federal Parliament will debate marriage equality once more, with Liberal Democrat senator David Leyonhjelm bringing a private members bill to legalise same-sex marriage today.

Senator Leyonhjelm hopes parliamentarians from all sides will back the proposed legislation, as it allows ministers and celebrants to refuse to preside over ceremonies if they object.

“All my bill does is prevent the Government from stopping two people from getting married on the grounds that they are not a man and a woman,” he said.

“It does nothing more, and it requires nothing more than tolerance.”

Senator Leyonhjelm says that while he does not believe the state should have a role in relationships of any kind, given that the regulation of marriage exists, it should not exclude people just for being lesbian, gay, bisexual, transgender or intersex (LGBTI).

“When the law says that LGBTI people can't marry, in an important sense, it is diminishing their liberty. A major choice is closed off,” he said.

“The state is interfering, intervening, telling certain people that they can do what they want, except when they can't, while everyone else, of course, can.”

The most recent attempt to update old values came last December, when the High Court unanimously ruled attempted ACT laws allowing same-sex marriage were out of line with the federal Marriage Act.

The Federal Government emerged victorious in the ruling, after it launched the appeal against the laws.

Just over a year before that, the House of Representatives voted overwhelmingly against legislation to allow same-sex couples to marry.

Ninety-eight members of Parliament voted against the bill put forward by Labor backbencher Stephen Jones, while just 42 voted in favour.