Today the Inner House of the Court of Session in Edinburgh ruled that questions over the UK's ability to unilaterally revoke the Article 50 notice to leave the EU given by Theresa May on 29 March 2017 should be referred to the Court of Justice of the European Union for authoritative determination.

The position of the MPs involved in the case, including Lib Dem Brexit Spokesperson Tom Brake and Labour's Chris Leslie, is that to discharge their responsibilities to the electorate, they and other Parliamentarians need confirmation from the European Court of Justice that the Article 50 notice can be unilaterally revoked by the UK in the event no withdrawal deal is agreed with the EU, or if what is agreed is unacceptable to Parliament.

The Court unanimously accepted this. Lord Drummond Young said in a concurring Opinion:

The fundamental argument for the petitioners is that, in casting their votes on the proposed withdrawal of the United Kingdom from the European Union, they should be properly advised as to the existing legal position. Their argument is, in essence, that in deciding what to do Members of Parliament should be able to consider a range of options...

I find it impossible to hold that the question of the withdrawal of the article 50 notification is a matter that is irrelevant to Parliament's deliberations. It is, moreover, an option that some Members of Parliament appear to consider significant. If Members of Parliament are to cast their votes in a responsible manner, it is surely obvious that they should be properly advised as to the existing legal position so far as that may be relevant to their deliberations...

It is then up to individual Members of Parliament to make what they will of the courts' advice. In these circumstances it cannot be said in my opinion that the question of revocation of the article 50 notification is merely academic or hypothetical. It is a matter that may, in some circumstances, be relevant to the way in which some Members of Parliament cast their votes on a matter of fundamental importance to the future of the United Kingdom.

Tom Brake said today:

Recent events in Salzburg show the UK is sliding towards a precipice. The judgment of the Inner House means the European Court now has the opportunity to confirm that the UK can unilaterally withdraw the Article 50 notice (something the government has constantly refused to admit). This would establish the UK's options to decide its approach to Brexit, democratically and positively, and underline that the choice for the UK is wider than just a revised version of Chequers or 'no deal'. This will be critical for Parliament over the next three months. We hope the Court will be able to confirm the position quickly.

Chris Leslie said:

It's clear that Parliament is going to have to step in and take over this process from Theresa May. If we're to do this and put the country first, we need MPs to realise that is not irreversible now. We cannot afford to be artificially constrained by the narrow view of a few Government Ministers with their own agenda any longer.

The Court's judgment (comprising three Opinions) is here and a summary is here.