Rights contained in the EU Charter of Fundamental Rights would continue to be protected in the UK after Brexit, under an amendment to the EU Withdrawal Bill approved by the House of Lords yesterday.
Peers voted against the Government by 316 to 245, despite ministers' claim that remaining in the charter would be a "constitutional outrage".
The Government is likely to attempt to reverse the change when the bill returns to the Commons.
The Charter provides separate guarantees of individual rights to the European Convention on Human Rights, in relation to questions of EU law, but some lawyers argue that even after UK law is converted into UK law under the bill, human rights protections will be weakened if the Charter is not kept in force.
Supporting the amendment, Lord Pannick QC said that excluding the Charter from UK law after Brexit would be a "recipe for confusion". There had been "no coherent defence of the Government's position". He asked whether the UK no longer trusted itself "to protect our own fundamental human rights".
Lord Keen of Elie QC, the Advocate General for Scotland, claimed in response that continuing the application of a foreign body of law after Brexit would be "the greatest constitutional outrage since 1689".
By the end of the day the Government had suffered a total of five defeats in the Lords over amendments to the bill. More contentious votes are expected before it completes its stages in the upper chamber.