Labour MPs are set to back an EU Withdrawal Bill amendment tabled by a Conservative rebel.
Dominic Grieve wants to see a charter of fundamental rights brought into UK law to make sure current human rights are not weakened after Brexit - including those which protect elderly people.
The amendment, already signed by 10 backbench Tory MPs, could gather enough support to defeat the government in a vote after Brexit debate resumes in the Commons on Tuesday.
Former Attorney General Grieve is one of at least 15 ‘Brexit mutineers’ expected to rebel against the government at critical points as the EU Withdrawl Bill moves through its tumultuous committee stage.
Keir Starmer, Labour’s shadow Brexit secretary, said: “Labour will not let the government use Brexit as an excuse to roll back fundamental rights.
“The charter is vital for ensuring the rights of people living in the UK are protected, including the elderly and those from the LGBT community. And yet, ministers want to drop it for the sake of appealing to the extreme voices in the Tory party.
“This week the government needs to change course or risk facing a defeat in the House of Commons.”
Britain is currently a member of the Charter of Fundamental Rights of the European Union, which sets out a range of civil, political and social rights for EU and UK citizens.
Until the UK formally leaves the European Union, EU law applies in the UK either directly in some instances, or when it is written into UK law, such as when an Act of Parliament is passed to apply an EU directive.
But its jurisdiction will no longer apply after the country leaves the EU in March 2019 and the EU Withdrawal Bill in its current form states: “The charter of fundamental rights is not part of domestic law on or after exit day.”
Labour said the charter is “vital for ensuring the rights of people living in the UK are protected, including the elderly and those from the LGBT community”, as it pointed to new research which reveals 36,485 – nearly one in ten – older people using social care services in England last year described their quality of life last year as bad, very bad or “so bad, it could not be worse”.
The government has claimed the Withdrawal Bill “does not remove any underlying fundamental rights or principles which exist”, but the Equality and Human Rights Commission says some rights, including those relating to children and older people, have no equivalent protection in UK law at a constitutional level.
Earlier this year, the commission’s chair David Isaac said: “We have been clear there must be no rowing back on people’s rights after we leave the European Union. Rights derived from the EU Charter of Fundamental Rights, including important protections for children and older people, must be preserved for UK citizens.”