The UK government has been warned its use of domestic legislation to override international treaty obligations with the EU would breach the Vienna convention, to which Britain is a signatory, as well as the ministerial code.
Brexit talks with the EU were thrown into chaos this week after the UK government introduced its internal market bill, which would override portions of the Northern Ireland protocol in the event of there being no trade deal with the EU.
However the weight of legal opinion is shifting against advice from the attorney general, Suella Braverman QC, and the solicitor general, Mark Ellis, who backed the plan. Senior lawyers have expressed amazement at their conclusions.
In a three-page letter seen by the Guardian that summarised advice from Braverman and Ellis, the pair in effect dismissed duties contained in the ministerial code as irrelevant and concluded that “international law is subordinate to the much more fundamental principle of parliamentary sovereignty”.
Philippe Sands QC, a professor of international law at University College London, said: “Every international lawyer is familiar with the Vienna convention on the law of treaties, and its article 27, which reflects a general principle: ‘A party may not invoke the provisions of its internal law as justification for its failure to perform a treaty’.
“There is simply no way around this binding rule – to opine that parliament is sovereign is, in this sense, hopeless.”
Ann Taylor, the chair of the Lords select committee on the constitution, wrote to the justice secretary, Robert Buckland, on Friday cautioning that: “Any breach of international law threatens to undermine confidence in future treaty commitments made by the UK government and increases the likelihood that the governments of other countries will breach their international law obligations.”
She also referenced the Vienna convention, saying article 60 states that a “material breach of a bilateral treaty entitles the other party to invoke that breach as a ground for terminating or suspending the operation of the treaty ‘in whole or in part’”.
Lady Taylor said the internal market bill put the entire withdrawal agreement, and other related agreements, at risk and “this would have far-reaching consequences”.
She also cited the cabinet manual, which says “ministers are under an overarching duty to comply with the law, including international law and treaty obligations…”, and the ministerial code, which states that there is an “overarching duty on ministers to comply with the law”.
In 2010 the code was more explicit, stating that there was an “overarching duty on ministers to comply with the law, including international law and treaty obligations”.
This second part was removed in 2015 under David Cameron’s administration, although the former Conservative minister Edward Faulks told the Lords at the time: “The obligations on ministers under the law, including international law, remain unchanged.”
A court of appeal judgment in 2018 confirmed that the code included the duty to comply with “international law and treaty obligations”.
Braverman and Ellis, however, claim the ministerial code only applies to UK law, putting them at odds with their fellow law officer, Richard Keen, the advocate general for Scotland, who advised that ministers would be breaching the code if they defied international law.
Mark Elliott, a professor of public law at Cambridge University, told the Guardian: “The attempt to suggest that [the code] does not now extend to international law is an attempt to shift the debate. It’s disingenuous to suggest that it’s consistent with the ministerial code [to break international law].
“Respect for the rule of law includes respect for international law, as the UK ministerial code used to make explicitly, and as is still – as the court of appeal has held – implicitly, clear in the current iteration of the code. The promotion by the UK government of [the internal market] bill that expressly breaches the UK’s international obligations is thus nothing short of extraordinary.”
The government also sought external legal advice before making its decision. It is unclear what advice they gave, but two of the three barristers chosen by the government to give advice on the legality of breaching treaty obligations – Prof Richard Ekins and Prof Guglielmo Verdirame QC – had previously made their views public.
In 2015, they co-authored a paper for the UK Constitutional Law Association advocating precisely the approach now adopted by the government. It said: “It would be wrong for ministers to be required to treat international legal obligations, including unincorporated treaties, as of equal standing to acts of parliament or common law duties.
“The rush to apply for such judicial control, as well as the assumption that international law should take precedence over constitutional law, tells us much – and none of it good – about modern legal thinking.”
A statement issued by the Cabinet Office on Thursday, defending government legislative plans, declared: “Parliament is sovereign as a matter of domestic law and can pass legislation which is in breach of the UK’s treaty obligations. Parliament would not be acting unconstitutionally in enacting such legislation.”
On Saturday, the attorney general may face sharp criticism over her stance on respecting international law when she chairs the Bar Council’s annual general meeting.