Before an Article 50 declaration can be issued, Parliament must enact a statute empowering or requiring the Prime Minister to issue notice under Article 50 of the Treaty of Lisbon, and empowering the Government to make such changes to statutes as are necessary to bring about our exit from the European Union.
Is this a mere formality? The political reality might be “yes”. Parliament might consider that following the referendum it must pass a statute in these terms. But the answer in constitutional terms is “no”. As a matter of constitutional law, Parliament is not bound to follow the results of the Brexit referendum when deliberating this legislation. A number of options are constitutionally open to Parliament.
First, it could decide not to grant this power at all. As some of the core claims made by the leave campaign unravel, Parliament might decide that the case for Brexit has not been made – or was gained under a false prospectus. As Edmund Burke taught us, ours is a representative, not a direct, democracy. Those representatives whose consciences required them to reject the referendum vote would have to justify themselves to their electorates at the next General Election – an event that is likely to arrive quite soon. We should make clear that we take no position as to whether Parliament should adopt such a course, but it is undoubtedly open to Parliament as a matter of constitutional law. Parliament is, after all, sovereign.
Secondly, Parliament could conclude that it would be contrary to the national interest to invoke Article 50 whilst it is in the dark about what the key essentials of the new relationship with the EU are going to be, and without knowing what terms the EU is going to offer. Parliament might well conclude that to require the Government to issue the notice immediately would be contrary to the national interest, even if Parliament is committed to leaving the EU, because the legal structure of Article 50 would place the UK at a seriously disadvantageous position in negotiating acceptable terms. Surely, Parliament is unlikely to require the Government to issue notice under Article 50 if it considers that the Government might be forced to accept exit terms which do not protect key aspects of our economy. Parliament may therefore require the Government to engage in extensive informal negotiations or even to seek to negotiate exit from the UK by formal Treaty amendments rather than through the Article 50 process.
If the UK seeks to obtain some form of framework agreement on key terms before invoking Article 50, once these terms are in place, Parliament could then trigger the Article 50 procedure to effect exit, perhaps with only details left to negotiate by the Government. Immediately upon an agreement being finalised the UK would no longer be part of the EU. This option would comply with the outcome of the referendum.
Finally, of course, Parliament could decide to authorize notice under Article 50 at once by empowering the Prime Minister to issue the declaration.