Wightman and the revocability of Article 50

Significance of Wightman: 

In the much-publicised case of Miller last year, the Supreme Court held that the UK Government could not
trigger Article 50 of the Treaty on European Union (TEU) without Parliament's consent. However, the Court
did not determine whether the subsequent notification under Article 50 could be revoked – indeed, both sides
agreed that it could not. Now, the petitioners in Wightman are seeking to have this question resolved.

The petition was initially rejected in February on the basis that it was "hypothetical" and "academic" and so the
successful appeal is significant even before the ECJ give their answer. The Scottish court decided that the
question was "neither academic nor premature" and that the answer was crucial for clarifying the options of
MPs in the lead-up to any vote ratifying or rejecting an agreement between the UK Government and the EU
Council.

The political importance of this question means that there have been passionate proponents of both sides of the
debate. The novelty of the issues to be decided makes the outcome uncertain but the political ramifications are
likely to be significant, whichever way the decision falls.

Article 50

Article 50 lays out the process for a Member State to withdraw from the European Union, specifying that
withdrawal will take place two years after the Member State in question gives notice of intention to do so (or
earlier if agreement is reached). Article 50 is wholly silent on whether this notification can be withdrawn
without the agreement of the remaining Member States, although there are aspects of the wording which
suggest the ability to withdraw the notice:

• The purpose of the notification is to signal an "intention" to withdraw, which is not indicative of being a
  binding commitment.
• The re-joining process referred to in the Article is specifically stated as being relevant to states who have
  "withdrawn" not those who have simply notified.
• The crucial absence of any express provision stating that a Member State has to re-join anew once
  notification is made, or that it cannot be revoked.

What is the significance of the automatic termination after two years?

Those arguing against revocation point to the two-year notice period as being inconsistent with a right to
revoke the notice. However, it could also be argued that the two-year notice period exists to provide a fixed
period of negotiation for a withdrawal treaty, avoiding the possibility of negotiations over an indeterminate
period. Revocation of the notice to withdraw would also achieve the effect of ending uncertainty.

As to the entirely valid concerns expressed over the potential for abuse of process if a Member State unilaterally
withdraws a notification only to re-notify and extend the two-year deadline, arguably a withdrawal of
notification should be allowed if it is made in good faith.

What role does customary international law play?

Article 68 of the 1969 Vienna Convention on the Law of Treaties provides that a notification of withdrawal from
a treaty may be revoked at any time before it takes effect. Some argue that Article 68 is representative of
customary international law and that the absence of an express prohibition on revocation in Article 50 means
that the ECJ is bound to interpret Article 50 as importing the right to revoke under the Vienna Convention.

Article 50 appears in the Treaty on European Union, which is governed by EU law, not public international law,
but ultimately, it will be up to the ECJ in this case to decide if Article 68 of the Vienna Convention applies to
the process under Article 50.

What next?

This case raises difficult questions of EU and international law on which there is little precedent, so the ECJ
decision is uncertain. There are good arguments in favour of interpreting a withdrawal right into the Article 50
process, and indeed, Lord Kerr, one of the drafters of the provision, has spoken out to say that it was intended
for Member States to be able to change their minds if necessary.

The UK Government has expressed disappointment at the Court of Session's ruling, reiterating their
commitment to Brexit regardless of the ECJ's ruling in November. It has recently applied for permission to
appeal the Court of Session's decision to the Supreme Court and that application will be heard on 8 November.
In the meantime, the ECJ referral will proceed. Assuming that the referral is neither withdrawn nor stayed
following the 8 November application, whatever the outcome, the ECJ's decision is likely to be significant, not
least for MPs deciding whether to accept an imperfect withdrawal deal presented to Parliament or to reject it
and face a no-deal scenario. We will keep you posted.