It is Rose Slowe’s   contention that, without a further Act of Parliament specifically authorising Brexit in one form or another, the United Kingdom cannot leave the European Union as a matter of law and the European Union will not be able to expel it.

The following is an extract from Rose Slowe’s BBC interview.

What does Article 50 actually mean in terms of leaving the European Union?

The Article 50 process is that which has been laid down by the EU in its Treaties setting out the way in which a Member State can leave the Union. There are a number of sub provisions in Article 50. They specify, quite importantly, that a Member State can only leave in accordance with a decision that is taken in a constitutionally compliant manner. So, for example, an authoritarian leader could not take a Member State out of the European Union in breach of the domestic constitution; withdrawal has to be done at the Member State level in a constitutionally compliant way.

Article 50 also provides that the leaving Member State must notify the European Union of its intention to leave, which the United Kingdom did; that was the Article 50 notice issued. Then, after 2 years, if these steps have been completed, the EU Treaties cease to apply to that Member State, they have effectively left the Union, unless, and this has happened in the UK’s case, the European Union decides to extend that period. This period has been provided for so that the Member State which is leaving can negotiate a withdrawal agreement with the EU.

So, it has to come down to Parliament passing a law saying that the United Kingdom can leave the European Union?

Yes, in the United Kingdom’s case, because a fundamental principle of the UK’s unwritten constitution is that Parliament is sovereign. We had the Supreme Court look at this issue in the Miller litigation and rule that it was Parliament – our elected legislature – that brought us into the EU with the 1972 European Communities Act and so it can only be Parliament, and not a Government or Prime Minister, that can take us out of the EU in accordance with the constitutional principle of parliamentary sovereignty. That is specific to the UK’s constitution; it has to be Parliament that legislates to take us out of the European Union.

What would happen if, as has been mooted, Boris Johnson suspends parliament to enable the Brexit process to take place?

He simply cannot do that as a matter of law. The Supreme Court has already held that the Government alone cannot bring the country out of the EU, it has to be by an Act of Parliament. So, any attempt by the Government to do that would not be legally effective, they just do not have the power.

Does this mean we are less likely to leave the European Union on 31 October?

Unless there is an Act of Parliament authorising a no-deal Brexit, or Brexit on the terms of a withdrawal agreement, legally the United Kingdom will not be leaving the European Union. On my interpretation of the constitution and EU Treaties, Brexit will not take effect without a further Act of Parliament authorising it in one form or another.

Can the European Union actually throw the UK out if they decide that they have had enough with everything?

A founding principle of the European Union is that it shows deference to Member State’s national constitutions, this is a premise of EU law. Indeed, the need for a constitutionally compliant exit is specifically provided for in Article 50. So, if we had our Supreme Court determine that we require a further Act of Parliament in order to leave the European Union in a constitutional manner, the EU could not expel the United Kingdom if to do so would be in breach of our domestic constitutional requirements.

Even the European Union’s most sever sanctioning mechanisms that can be deployed against a Member State found to be in breach of the Union’s founding values does not allow it to expel that Member State. The EU simply does not have the power to kick out a Member State, it has to be the Member State’s decision to leave in one way or another and this decision has to be a constitutionally compliant one.

So, without a law passed by Parliament, and without the European Union having the jurisdiction to throw the United Kingdom out of the Union, the UK will just be left in a state of limbo?

Yes, we would simply remain a Member State. It is even arguable that the Article 50 notice issued would lapse and cease to be of effect as it has to be interpreted as being subject to the condition that it would be made effective by an Act of Parliament down the line; it was a conditional notice and if these conditions are not met it would just lapse and the UK would continue to retain its EU membership.

* Prior to joining the Bar, Rose Slowe LLM was an Honorary Research Fellow at the University of Bristol Law School. She co-authored a leading book on the European Union and the Council of Europe, published by Cambridge University Press. Rose has also published widely and debated in Parliament on matters pertaining to the interplay between the domestic UK and European legal orders.