Not long after the result of the referendum was announced, the heads of the EU institutions dismissed any speculation on whether Article 50 of the Treaty on European Union (TEU) could be circumvented. Pursuant to Article 50(2) TEU, the trigger to begin withdrawal proceedings lies with the departing country, the United Kingdom. Yet, the Treaty leaves open the "how and when": there is no deadline for triggering Article 50 TEU, nor are there requirements as to the format. In practice, this means that the UK is not obliged to begin withdrawal proceedings and that it can wait until it decides it is appropriate to do so. Meanwhile the EU is putting pressure on the UK to kick-start the procedure.

The UK's position

At first, and contrary to his earlier statements, outgoing British Prime Minister David Cameron stated that his successor would be the most appropriate person to start the procedure. However, Prime Minister Theresa May has already made it clear that she will not trigger Article 50 until a clear national plan on the way forward and how to approach the negotiations is put together and agreed within the UK. "I have already said that I won’t be triggering Article 50 until I think that we have a UK approach and objectives for negotiations", stated May. Once the British Prime Minister has triggered Article 50, the withdrawal negotiations with the EU will begin. It is from this moment that the two-year period runs within which the EU and the UK have to negotiate (and ideally conclude) a withdrawal agreement.

By delaying the formal notification of its withdrawal, the UK is gaining time to come up with a clear domestic plan regarding future relations with the EU. This will define the British position going into the actual negotiations. As Prime Minister May stated before entering office, the decision to "push the button" is not likely to take place until 2017. The UK High Court has now also received legal challenges arising from the Brexit referendum result, claiming that only Parliament (and not the Prime Minister) can trigger Article 50 proceedings. It is likely that the case will be sent to the highest UK Court, the UK Supreme Court, on an expedited basis. A decision is expected by the end of 2016.

Nevertheless, in July 2016 the UK sent the first signals that it is preparing to leave the EU, announcing it would relinquish its Presidency of the Council of the EU in the second half of 2017. (Estonia will step into the UK's void six months ahead of its scheduled Presidency.) This announcement has reassured those who were starting to doubt whether Article 50 would ever be triggered. Another indication in this regard is the fact that the UK's Permanent Representation to the EU now reports to a new Department for Exiting the EU, also known as "Dept X" and headed by Secretary of State for Exiting the EU David Davis, instead of reporting to the Foreign Office, as traditionally has been the case. A new Department for International Trade has also been set up.

Meanwhile, in Brussels and other EU capitals, there is some anxiety about when the procedure will begin, as a result of what has been perceived as British delaying tactics.

The EU's push to move forward

Just days after the British referendum, the EU was already pushing forward. In a joint statement issued by the 27 remaining Member States on 29 June 2016, EU leaders made it clear that the UK should trigger Article 50 TEU "as quickly as possible", warning that "there can be no negotiations of any kind before this notification has taken place."

The EU has also recently appointed Michel Barnier, former French Minister and former Commission Vice President, as Chief Negotiator in charge of the preparation and conduct of the negotiations with the UK under Article 50. This clears any confusion that resulted from the appointment of Belgian diplomat Didier Seeuws by Council President Donald Tusk to head a "Special Task Force on the UK Brexit". Barnier will manage the (technical) bulk of the negotiations, while Seeuws' role will be more of a coordinating nature, protecting the prerogatives of the Council (and hence the EU Member States) against potential infringements by the European Commission.

The EU's tough stance regarding the timely triggering of Article 50 TEU reflects the remaining Member States' unease with what has been perceived as a string of measures to cater to the UK's position after Prime Minister Cameron's re-election in 2015 and ahead of the 23 June referendum, especially after the 27 Member States renegotiated the UK's membership with then Prime Minister David Cameron in February this year. Moreover, there is a strong sentiment among parts of the EU that the EU should not be held hostage by the UK's internal political developments following the vote. The EU is also facing a multitude of challenges, ranging from the migration- and refugee crisis to socio-economic challenges. The EU's view is that delaying the UK's exit is therefore not in the interest of the other 27 Member States.

In order to force the UK's hand, some think that the EU should trigger Article 7 TEU:

Article 7 TEU

(ex Article 7 TEU)

1. On a reasoned proposal by one third of the Member States, by the European Parliament or by the European Commission, the Council, acting by a majority of four fifths of its members after obtaining the consent of the European Parliament, may determine that there is a clear risk of a serious breach by a Member State of the values referred to in Article 2. Before making such a determination, the Council shall hear the Member State in question and may address recommendations to it, acting in accordance with the same procedure.

The Council shall regularly verify that the grounds on which such a determination was made continue to apply.

2. The European Council, acting by unanimity on a proposal by one third of the Member States or by the Commission and after obtaining the consent of the European Parliament, may determine the existence of a serious and persistent breach by a Member State of the values referred to in Article 2, after inviting the Member State in question to submit its observations.

3. Where a determination under paragraph 2 has been made, the Council, acting by a qualified majority, may decide to suspend certain of the rights deriving from the application of the Treaties to the Member State in question, including the voting rights of the representative of the government of that Member State in the Council. In doing so, the Council shall take into account the possible consequences of such a suspension on the rights and obligations of natural and legal persons.

The obligations of the Member State in question under the Treaties shall in any case continue to be binding on that State.

4. The Council, acting by a qualified majority, may decide subsequently to vary or revoke measures taken under paragraph 3 in response to changes in the situation which led to their being imposed.

5. The voting arrangements applying to the European Parliament, the European Council and the Council for the purposes of this Article are laid down in Article 354 of the Treaty on the Functioning of the European Union.

Another discussion which is gaining prominence in British academic circles is whether the UK, having triggered Article 50, can on a proper interpretation of that article revoke its notification unilaterally, or whether it is locked into a fixed two year exit period (absent mutual agreement with all remaining Member States to extend or withdraw). There is significant academic disagreement on this question within the UK. One side of the argument holds that Article 68 of the Vienna Convention on the Law of Treaties 1969 states that a party that gives notice of its intention to withdraw from a treaty can revoke that notice at any time before it takes effect. The other side argues that the TEU creates an autonomous legal order which should not be interpreted by reference to other external international standards, and thus Article 50 itself amounts to a complete code for withdrawal. The TEU itself is silent on the position.In a nutshell, under Article 7 TEU, the EU can suspend a Member State's voting rights if it considers that it has breached the common values of the Union (basic principles of freedom, democracy, equality and rule of law) as enshrined in Article 2 TEU. The successful triggering of Article 7 TEU would thus suspend certain of the UK's rights, including its voting rights in the Council, while the UK would continue to be bound by its obligations under the TEU. The argument goes that continued delay by the UK Government violates the common values of the Union. Namely, by delaying the triggering of Article 50 TEU the UK is not acting in solidarity with the remaining Member of the Union. This conduct, based on solidarity among EU Member States, is basically meant to prevent the pursuance of national interests by a Member State which is disregarding the effects its behaviour might create for the remaining Member States. The invoking of Article 7 TEU remains unlikely at this stage, particularly since it has never been triggered before. Yet, the mere threat of invoking the Article remains a powerful instrument in the EU's toolbox to prevent the UK from stalling the triggering of Article 50 TEU.

The question of whether the notice can be revoked or not could have considerable significance in terms both of tactics around any exit negotiations and also the timing of a decision to invoke Article 50. However, in the perception of the EU institutions and a majority of the remaining Member States, this seems to be more of a political question, rather than a legal question; there is general consensus in Brussels that once the UK triggers Article 50, there is no turning back.