Wayne Furbert’s bid to reverse the legalisation of gay marriage could put the United Kingdom in breach of its international obligations, according to lawyer Mark Pettingill.

Mr Pettingill, one of the lawyers who successfully litigated the case that led to same-sex marriage becoming legal, predicted the Governor may withhold assent for the Private Member’s Bill expected to be tabled by Mr Furbert in Parliament today.

The proposed legislation seeks to restrict marriage to opposite-sex couples and, if approved, would make Bermuda the first country in the world to do an about-turn on the issue.

On the eve of the new government’s first Throne Speech, in which it may outline its plans for a gay marriage alternative, Mr Pettingill said: “The British Government is faced with a very significant issue.

“[Mr Furbert’s] particular amendment would put the UK in breach of its international obligations. The Governor, in assenting, has to look at the position.”

Bermuda’s Constitution, under section 35, enables the Governor to “reserve for Her Majesty’s pleasure” any Bill inconsistent with the obligations of the British Government towards any other international organisation.

One such body is the European Court of Human Rights, which has ruled there must be state recognition and protection for same-sex couples, although not necessarily through marriage.

Mr Pettingill claimed approval for Mr Furbert’s Bill would put the UK in breach of that, even if Bermuda had plans for an alternative framework giving the same rights as marriage.

“The problem with that is that it’s already been done,” he said. “The framework is in place.

“People have married under a certain scheme. You can’t go ahead and say ‘we are going to remove that scheme’ and later try to impose another scheme. You are going to leave a void in the law.”

Mr Pettingill said the Governor, in deciding whether to give assent, would also consider whether the Bill was consistent with the Constitution, which gives every person in Bermuda the right to freedom of expression, freedom of association and the protection of the law.

Fellow lawyer Rod Attride-Stirling, who represented the Human Rights Commission in the same-sex marriage Supreme Court case, agreed the Bill could create legal problems, particularly regarding same-sex couples who have married here since the May 5 ruling.

“If you look at the Bill, on its face, it would render all same-sex marriages void,” he said. “It doesn’t include a grandfathering clause to protect the existing ones. I would be surprised if the Governor were to sign it.

“The Bill in its present form takes away crystallised rights retroactively. That is unconstitutional which makes it legally inappropriate for the Governor to sign it.”

Same-sex marriage opponent Charles Jeffers said it would be wrong for the Governor to act against “the will of the people” and refuse assent.

“I don’t care what they do in Britain,” he said. “I do not believe that a governor should be taking a position that’s contrary to the views of our Parliament and to the people whom they represent.

“I have relatives, I have friends who are gay and I am certainly not going to shun them because they are gay. But I am not sure this is a human rights issue.”

LGBT civil rights organisation Human Rights Campaign confirmed yesterday that if Mr Furbert’s Bill became law, Bermuda would be the first country to reverse a decision to allow same-sex marriage.

Ty Cobb, director of HRC Global, said: “To do so… would be similar to what transpired here in the United States in California — where marriage equality began and was taken away through a ballot measure that was ultimately overturned by the US Supreme Court.

“This created mass chaos and harm, especially for legally wed same-sex couples and their families.”