Michel Barnier has very politely confirmed that the EU will be suing the UK in a respectful manner. That has all the validity of a child using his younger brother's arm to hit his own face while stating, 'why are you hitting yourself?'. Passive aggression is still aggression. Suing someone is an aggressive act.
Now, as I sue people for a living, it would ill behove me to argue that the EU must not ever sue the UK. It is a political question on which people will naturally disagree.
There is however an important legal question — whether or not the EU can sue the UK in law. It is unfortunate for the EU that a consensus has emerged amongst lawyers that the EU has no grounds for suing the UK; it has no case.
Even someone who supported the EU suing the UK would be unlikely to support it doing so when it has no case.
The reason the EU has no case is itself relatively simple — they’ve acted too soon. The issue at hand is the Internal Market Bill. An Act is law; a Bill is a proposed law. Until a Bill is an Act, it’s nothing.
The EU is basing its legal action on the idea that the UK has breached Article 5 of the Withdrawal Agreement. This article states:
“The Union and the United Kingdom shall, in full mutual respect and good faith, assist each other in carrying out tasks which flow from this Agreement They shall take all appropriate measures, whether general or particular, to ensure fulfilment of the obligations arising from this Agreement and shall refrain from any measures which could jeopardise the attainment of the objectives of this Agreement. This Article is without prejudice to the application of Union law pursuant to this Agreement, in particular the principle of sincere cooperation
The important bit is in italics. The EU is now trying to argue that the UK has made a measure that jeopardises the Agreement. Sometimes legal questions are tricky. This is not tricky. The UK hasn’t made an Act yet. It hasn’t 'made' anything because a Bill is not an Act. As a result it certainly hasn’t made a measure.
If the Bill becomes an Act will that be a measure? I doubt it because the definition of measure in EU case law is more demanding – although, any fight over this point won’t use EU law to answer what a measure is. But until there is an Act, I don’t see anyone who would argue there is a measure and the legal consensus on this has been edifying.
It is sometimes argued that international law is more important or challenging than domestic UK law. In fact, the reverse is true. International law has to function for the needs of the 193 nations and whatever entity the EU is. As a result, it is much simpler than our law – which has to regulate a complex 21st-century economy and control really very detailed matters.
International law has to be more accessible and it is. As a result, there is no principle of an action that is an anticipatory breach. You can’t break international law by declaring you may break it in future (our laws are more strict) because such a principle would be unworkable in trying to govern 193 cultures (and whatever the EU is). You only break international law if and when you break it.
As a result, the EU has no case. I do not therefore need to comment on whether it is helpful or a good idea to suddenly sue a negotiating partner (and ally) during a negotiation. I do not need to address the very real concerns many lawyers now have as to the independence of the ECJ.
The EU’s letter is not law, it is politics. It is, I think, a misjudged piece of negotiation theatre, but tastes in theatre differ. The EU should withdraw the letter and the negotiation should go on because real people across the UK and the EU really need a deal. No one needs theatre 51 months into a negotiation.