A historic ruling to legalise same-sex marriage in the Cayman Islands could have a domino effect across the British Overseas Territories, according to a leading human rights lawyer.

Jonathan Cooper, QC, who served as an adviser to the legal team that brought the successful court challenge, said the decision should be welcomed.

He believes it will force the U.K. to take more direct action to intervene in other territories, including the British Virgin Islands, Anguilla and Montserrat, which still outlaw same-sex marriage.

“The writing is on the wall,” he wrote in an emailed response to questions from the Cayman Compass. “The Foreign and Commonwealth Office will now have to provide for the legal recognition of same-sex relationships across all the UK Overseas Territories.”

The governor, who was named as a defendant in the legal challenge along with the government, endorsed Chief Justice Anthony Smellie’s decision on Monday, saying it provided “equality for all”.

Premier Alden McLaughlin is expected to make a statement on the issue in the Legislative Assembly on Wednesday.

Opposition leader Ezzard Miller, speaking at a press conference Tuesday, said he supported civil unions for same-sex couples rather than marriage. He said he was concerned that the chief justice was able to amend the islands’ laws and said he did not believe the constitution entitled him to do this.

He said this element of the ruling had serious implications for democracy in the Cayman Islands and should be appealed all the way up to the Privy Council.

Chief Justice Smellie said in his ruling that Section 5 of the Constitution allowed him to modify laws that were not compatible with freedoms guaranteed under the Bill of Rights. He changed the Marriage Law to allow same-sex couples equal access to marriage.

Cooper, also editor of the European Human Rights Law Review, said he believes Cayman has nothing to fear from affording equal rights to same-sex couples.

“The guarantee of equal marriage makes society safer, more stable and more secure. Denying human rights to some and preventing them from having full access to citizenship has a knock-on effect which impacts everyone,” he said.

“With the deprivation of human rights comes costs. Diverse, inclusive societies are more prosperous and happier.”

The Cayman Islands Human Rights Commission also expressed support for the decision, congratulating Chantelle Day and Vickie Bodden Bush on their successful legal challenge to the “discriminatory provision of the Marriage Law”.

Describing the judgement as a “tremendously significant constitutional law ruling”, the commission’s statement highlighted the chief justice’s finding that “no justification” had been established to support the “severe form of discrimination” of a same-sex marriage ban.

It said, “This judgment should be welcomed by all in our community. In modifying the Marriage Law, the chief justice has affirmed the constitutionally protected rights of Vickie and Chantelle and many others in committed same-sex relationships. Equally, the rights and freedoms of all other individuals in the Cayman Islands, including rights of religious freedom, are similarly affirmed and protected.”

The Human Rights Commission also addressed the issue of the chief justice’s powers to amend legislation. It stated that once he had ruled the Marriage Law was unconstitutional and unlawful, he was “required by the mandatory terms of the Cayman Islands Constitution” to modify the offending sections of that law.

The ruling was effective immediately, meaning same-sex marriage has been legal since Friday in the Cayman Islands.

A spokesperson for the government’s General Registry said Tuesday that it had received no requests since then from same-sex couples seeking a licence to marry.

“The usual process is for an application to marry to be made to a Marriage Officer. Once the marriage has taken place, it is then submitted to the Registry for registration,” she said in an emailed response to questions from the Compass.