The government may be forced to explain its plans for gay marriage in the House of Commons today if an urgent question is granted. Chief among the questions from backbenchers will be the consequences for religious institutions that continue to oppose the idea and do not want to conduct such ceremonies.

There are some Tory MPs who are viscerally opposed to the idea of gay marriage in any form, but others are wavering and need reassurance that they will not vote for something which leads to the situation where a vicar is forced as a result of a European Court judgement to conduct a same sex marriage against their will. Cameron was at great pains to stress on Friday that no-one would be forced to conduct ceremonies they disagree with, but the question is whether he has the legal advice to back this confidence up. Today his spokesman said:

‘We do not publish legal advice. What he has said and what we will do is make absolutely clear that if a church or a synagogue or a mosque does not want to have gay marriage, then it does not have to and it will not be forced to.’

He added that the government ‘does take legal advice on issues’, but that the results of the consultation on gay marriage have not yet been made clear.

One senior Tory I spoke to recently told me that they would only rebel against the legislation if they didn’t have the confidence that religious institutions which oppose the ceremonies aren’t protected. It is also something that backbencher Mark Pritchard has warned about, saying:

‘The Prime Minister is no doubt well-meaning for protections for faith groups – but it is not in his gift to offer legal guarantees. A test case will soon be brought before the Supreme Court of ECHR which could rule such protections are unlawful.’

Although the government says it does not publish its legal advice, ministers will need to make absolutely clear that they have a watertight case for the opt-in style system that they are proposing.

Tags: Conservatives, Gay Marriage, UK politics