Democratic Unionist Party MP Jeffrey Donaldson has said his party believes in devolution and matters such as marriage and abortion are a matter for the Northern Ireland Assembly.
The House of Commons voted overwhelmingly yesterday to legislate for marriage equality and abortion in Northern Ireland, unless the government at Stormont is up and running again by 21 October.
However, Mr Donaldson, speaking on RTÉ's Morning Ireland, said that the proposals breach the devolution settlement and undermines the concept of devolution in Northern Ireland.
These sensitive issues cannot, he said, be amended once passed.
Mr Donaldson added that while he believed in democracy and accepts the vote of parliament, democracy should also be accountable and allow the opportunity for people to make changes.
"It really is a matter for the people of Northern Ireland, through their elected representatives, to take the decisions and to make the law on these issues," said Mr Donaldson.
"To do it in the way that it is proposed now, not only breaches the devolution settlement and undermines the concept of devolution and political institutions in Northern Ireland, it's not a good way to make law."
Meanwhile, Amnesty International, has said yesterday's "landslide" votes in the House of Commons was a just reward for years of campaigning by grass roots groups and NGOs.
Abortion is strictly limited in Northern Ireland and same-sex marriage is illegal.
Also speaking on Morning Ireland, Amnesty's director in Northern Ireland, Patrick Corrigan, said the outcome was no great surprise as campaigners have been working the ground diligently over the last couple of years.
Mr Corrigan said they knew that - barring the DUP's ten MPs - it had support from all of the other significant parties.
He said it was a matter of getting the right legislative vehicle, at the right time, in the right chamber.
They could no longer do it at Stormont, he said, and that is why it was brought to Westminster.