Power to let ministers change UK law attacked
Meanwhile, a move to give ministers the power to change UK law in implementing international legal agreements post-Brexit has faced a barrage of criticism by peers.
Members of the House of Lords raised constitutional concerns over the provision contained in legislation currently going through the upper chamber, warning it was "wholly inappropriate" and "goes too far".
The Private International Law (Implementation of Agreements) Bill will enable the introduction of international rules used to deal with cross-border legal disputes after leaving the EU.
However, in a change to a long-standing convention, the bill seeks to give the British government the power to enact such agreements by using secondary legislation, known as statutory instruments, rather than requiring an Act of Parliament.
The Lords Constitution Committee has already branded the move "unjustified and ill-considered".
Speaking during detailed scrutiny of the bill at committee stage, Shadow Attorney General Lord Falconer of Thoroton told the virtual proceeding: "What it allows the Government to do is by delegated legislation to change the law of the country... to give effect to agreements that they have entered into in private international law.
"As a matter of constitutional propriety this is wrong."
He argued against giving the Government "this wholly inappropriate power never used previously and for which no proper justification has been given".
Leading lawyer Lord Pannick said the measure "raises matters of considerable constitutional concern".
He said: "The concern is that, with the exception of EU law from which we are extracting ourselves, it is a fundamental principle of our constitution that international agreements can only change the content of our domestic law if and when they are given force by an Act of Parliament."
"We think there is no justification... for allowing our law to be changed by statutory instrument without the need for full parliamentary debate."
Lord Pannick argued the measure "would not just allow for the implementation of the text of the international agreement, it will allow for consequential and supplementary and incidental provisions".
He said: "It will allow ministers to create by statutory instrument new criminal offences.
"These are matters for detailed scrutiny of a bill through the various stages of the parliamentary process."
Stressing the need to "maintain ministerial accountability to Parliament", Lord Pannick added: "This is not emergency legislation.
"It is a proposal for a permanent shift in power to the executive."
Former deputy president of the Supreme Court Lord Mance argued that the measure "simply goes too far".
He said: "Direct parliamentary legislation is possible and appropriate.
"It is implausible for the Government to suggest that either speed or reputational risk requires for the first time in history so unlimited... a delegated legislative power to implement any future private international measure agreed at the international level."
He added: "I suggest, therefore, that the Government should think again about the desirability of dealing with important, even though they can be technical, matters in the manner proposed indefinitely."
Labour peer Baroness Taylor of Bolton, chairman of the Lords Constitution Committee, said members felt it was "wrong that international agreements should be dealt with by the Government through secondary legislation".
"I certainly hope that the Government will think again about this," she added.
The former chief justice of England and Wales Lord Judge said: "The bill unnecessarily vests excessive power in the executive by means of secondary and not primary legislation."
Responding, Ministry of Justice spokesman Lord Keen said restricting the ministerial power would "prevent the United Kingdom from implementing any future agreements in a timely manner".
He said: "That in turn of course is going to delay the benefit of those agreements to both citizens and businesses.
"I would regard that as a unsatisfactory position given that in many cases there is considerable advantage to be gained from such international cooperation in the area of private international law."
Lord Keen added: "I submit that it is in the UK's interest to implement private international agreements in domestic law... without the delay that would inevitably arise if primary legislation were required on each occasion.
"This power I submit is both reasonable and proportionate.
"Delays in regard to this matter would be detrimental."
While there are currently no facilities for electronic voting for the Lords remote proceedings, peers indicated their opposition to the measure.
It sets the scene for a future showdown and possible UK government defeat when the bill returns at report stage.