To my understanding, the lawful government of the united kingdom has decided, following due process, that:

• 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

Given that, what happens when the set date arrives? (Whether that is 29 Mar, or an extension is appplied for and granted)

Can EU27 simply assume that "Since your parliament ruled out both the negotiated deal and a hard brexit, we assume that all treaties are still valid."?

Can EU27 simply assume that "Since you did trigger article 50 and declined the negotiated deal, we (regretfully) assume that all treaties now are void"?

EU27 are supposed to honor the decisions of UKs legal government, but what are the options if the stance of that government is literally "we cannot decide"?

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

That is not a legal decision. This is just a wish that Parliament has expressed.

If nothing else changes, as things currently stand¹ (2019-03-14T09:09Z) the UK will leave the the EU without any agreement on 29 March, against the wishes of Parliament. To change this, the UK must either:

• Unilaterally withdraw article 50 and cancel Brexit;


• apply for an extension, which must be approved by the EU and its member states;


• or accept the Withdrawal Agreement.

¹The situation is rapidly changing. This answer may be out of date within 12 hours of being written.

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 communicatedin writing to the European Council.

Such a revocation confirms the EU membership of the Member State concernedunder 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 has 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, 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 precident.

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, 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.