Given the massive political crisis that Brexit is causing in the UK – and the unprecedented union and unison of all 27 Member States on the issue over the past 3 years – one may be tempted to overlook the constitutional issues that a further extension of Article 50 would create for the EU.

However, in any Parliament maths are important: having (or not having) 73 British MEPs will have major implications on the next European Parliament.

Following yesterday’s decision to grant the UK a Brexit extension until 31 October, the UK will have to hold EU elections and send representatives to the European Parliament, and may even appoint an EU Commissioner. It is clear that, as long as the UK does not ratify a Withdrawal Agreement, it is still a Member of the EU, enjoying the full rights of membership. However, one issue remains unclear: when will British MEPs ultimately leave?

There are two solutions, and both of them have the potential to give the civil servants in the Commission’s legal department headaches and insomnia:

1. La loi, c’est la loi: MEPs, British or not, are elected for a mandate of 5 years.

In that scenario, even if the Withdrawal Agreement is ratified by 31 October, Brits in the European Parliament will stay until the end of their mandate, in 2024.

Surely that will infuriate President Macron: the Frenchman will not let a Brit (much less dozens of them) crush his hopes and hold the power to decide the EU’s fate when the UK will cease to be a Member State. This would be enough to make Charles De Gaulle turn in his grave! Part of the discussion yesterday in the Council (10 April) was specifically focused on limitations on the UK’s influence over key decisions such as the EU budget on which the Parliament has the last word.

2. Leave means leave: British MEPs are elected for as long as the UK is a Member and will leave after the Exit Deal ratification.

Supposing the UK government and the House of Commons sort things out by the end of October and ratify a deal, all British MEPs will leave Brussels (and Strasbourg) by then. It seems simple enough.

However, the EU had drawn up a full plan for the ‘after-Brexit’ European Parliament, which included 705 MEPs (instead of 751) and foresaw a redistribution of seats (with some Member States gaining up to 5 seats compared to the last legislature). How could the EU implement this plan in the middle of the legislative work? How could Member States send additional MEPs to the European Parliament based on elections that happened over 5 months before? Would the EU scrap this after-Brexit plan altogether and spend 2020 to 2024 with 679 MEPs? Here’s your headache!

Again, maths are important in a Parliament: changing the number of MEPs during the course of the legislature could have a significant impact.

Political groups in the European Parliament are formed by at least 25 MEPs from at least 7 different Member States. Although the results of EU elections in the UK are largely unpredictable at this stage, the current ECR group would be likely to keep some British Conservative members and (if the decline of the centre-left is confirmed across the EU) could become the second biggest group. Alternatively, should Labour win a lot of MEP seats, that may strengthen the S&D Group.

And the bigger the political group, the more high-level positions it has, starting with the Presidency of the European Commission. The ‘Spitzenkandidat process’ consists of appointing the candidate of the political party capable of marshalling sufficient parliamentary support as European Commission President. Changing the number of MEPs might mean changing majorities, and it could be that the next European Commission President might not have enough support from the Parliament after British MEPs leave.

Similarly, the bigger the political group, the more opportunity it has to chair parliamentary committees. If British MEPs become Chairs, redistributing these roles after their departure will likely prove to be difficult, especially if a future conservative political group collapses when they leave.

For a country that wants to be out of the EU, the UK stands to have a massive impact on the future of the Parliament – potentially affecting the system until the next European elections in 2024. The liberal pro-European leaders of Belgium, the Netherlands, France and Denmark have already voiced their opposition to a system that would render the EU a hostage of the UK; while some Brexiteers might see these elections as a last attempt at glory. With uncertainties looming ahead, it seems that the ghost of Brexit may haunt Brussels for a little while longer…