The EU isn't going to assume anything.

Article 50 is a formal process, triggered by the UK. If the UK neither accepts the deal, nor asks and get granted an extension, nor withdraws its intention to leave the EU, the UK will leave the EU, 00:00 March 30, 2019 (Brussels time). That's what the Article 50 procedure mean.

Everything between the EU and the UK follows a set procedure, and it's (mostly) the UK who determines which direction it goes:

1. The UK accepts the deal. Then the UK leaves the EU on 2019-03-30 00:00 with a deal. Else,


2. The UK withdraws its intention to leave the EU. Then the UK stays in the EU. Else,


3. The UK asks for an extension, and the EU grants that extension. Then we go back to point 1, but with a different date. Else,


4. The UK leaves the EU on 2019-03-30 00:00 with no deal.

No assumptions by the EU.

The EU can't force the UK to stay. The UK can unilaterally withdraw from the treaties that make it part of the EU. The EU continuing to act as if the UK had not withdrawn would be pointless and detrimental to the EU, as the UK would not be obliged to follow any of the rules any more and thus have a huge trade advantage.

The UK could ask for an extension to the Article 50 process, which the EU could accept or deny.

The UK could unilaterally cancel brexit by withdrawing its Article 50 notification. EU courts have ruled that this is possible if done in good faith.

If the UK simply fails to make any decision then it will crash out of the EU on March 29th and there is little that the EU can actually do about it.

We cannot know

Brexit or not is determined by EU law and politics and by UK law and politics at the same time.

EU Law

The European Court of Justice has ruled

The revocation must be decided following a democratic process in accordance with national constitutional requirements. This unequivocal and unconditional decision must be communicated in writing to the European Council.

Such a revocation confirms the EU membership of the Member State concerned under terms that are unchanged as regards its status as a Member State and brings the withdrawal procedure to an end.

UK Law

Parliament is sovereign, and it cannot constrain its future actions.

• The United Kingdom shall leave the European Union at a set date (currently 29 Mar 2019)


• The United Kingdom shall not accept the deal negotiated with EU27


• The United Kingdom shall not leave the European Union without a deal

These are in order. If later actions by Parliament conflict with earlier ones, the later actions win.

So currently, Parliament has stated "the UK shall not leave the EU without a deal". Any act of Parliament prior to that doesn't contradict it; it contradicts any earlier act.

On the other hand, Parliament has arguably not made an unequivocal and unconditional decision and communicated it to the European Council in writing (that last part is easy; someone can print out the bill and literally walk it over; the first part, less so).

The decision that the UK Parliament made is conditional (on no deal being made), or at least equivocal in its conditionalness.

Or, arguably, the UK has through its democratic process, in accordance with national constitutional requirements, now stated that at the end of March it will have withdrawn from Article 50 if there was no deal in place or extension; at that point, there is remaining condition, and "we won't leave the EU without a deal" is unequivocal.

The meaning of this action could even be decided retroactively: Imagine the day after Brexit, everyone proceeds as if it was a hard Brexit. Borders clank shut, etc.

That very day, Theresa May loses the confidence of the House, she gets replaced by someone whose position is that UK never left the EU due to this resolution, and they convince the ECJ to agree with them.

Or the exact same narrative can occur, except the ECJ could say "no, that isn't how it works, please apply for membership again".

There is no clear answer. This is the realm of politics, optics, and law without precedent.

Words on TV by politicians or pundits could fundamentally change what this action means, long after the action's meaning has seemingly settled.

Enough people state "it is non binding", and that actually makes it less binding. Enough people state "it is binding, Theresa May can no longer legally leave the EU without a deal", and that actually makes it more binding. Because popular interpretation of what was done can sway what it means.

Repeal of key documents

There are two main documents that are currently valid and prescribe how and when UK is leaving EU.

European Union (Withdrawal) Act 2018

The key act of UK law regarding Brexit is the European Union (Withdrawal) Act 2018 which states, among other things, that according to UK law UK will be out of EU on March 29. Any changes to Brexit won't be implemented in due process until/unless this act is amended - every extension requires that. It's not an important thing politically because, really, if you've got a majority willing to make an agreement, then it's a triviality to pass a motion altering the dates in this act, but it must be done to take effect.

For example, as the 'rejecting no deal' motion doesn't amend this act, the current UK law still means that if nothing changes, UK will consider it out of EU on March 29 even without a deal.

It's worth to note what exactly did the motion actually say. It did not pass law that the United Kingdom shall not leave the European Union without a deal. The only mandate in that motion was to instruct the PM to seek an extension, while adding 'context' and reasoning for that extension that includes "This House [..] notes that this House has decisively rejected [..] the proposition that the UK should leave the European Union without a Withdrawal Agreement and a Framework for the Future Relationship" - it's a statement of intent and opinion, but it is not a binding act of law passed in due process as the EU Withdrawal Act is.

Article 50 request itself

From the perspective of EU, on the other hand, the invocation of A50 is the primary document. It's worth noting that A50 doesn't explicitly prescribe any means to cancel it, and the wording on extension is quite clear "The Treaties shall cease to apply to the State in question from the date of entry into force of the withdrawal agreement or, failing that, two years after the notification referred to in paragraph 2, unless the European Council, in agreement with the Member State concerned, unanimously decides to extend this period."

If Britain can't decide, then on the date where any possible extension ends, the EU27 must (there's no choice on their part) assume that since UK did trigger article 50 and no withdrawal agreement has been passed, then all treaties cease to apply to UK.

The only other option is the ECJ ruling on A50 revocation which states that if a member state changes its mind and wants to stay in EU, then it can do so. Quoting the ruling, "The revocation must be decided following a democratic process in accordance with national constitutional requirements. This unequivocal and unconditional decision must be communicated in writing to the European Council.
Such a revocation confirms the EU membership of the Member State concerned under terms that are unchanged as regards its status as a Member State and brings the withdrawal procedure to an end."

Obviously, at the moment UK has not made an unequivocal and unconditional decision that it wants to stay in EU and bring the withdrawal procedure to an end, and has not notified the European Council about this, so currently this doesn't apply.