A version of the EU's proposed "Draft text of the Agreement on the New Partnership between the European Union and the United Kingdom" is available here (this may be a leaked version, with some edits before an official one is published). There's a lot in this document to discuss! I'm going to start with a follow up to this post. Here is a provision in the dispute settlement part related to questions of interpretation or application of European Union law:
Article INST.16: Disputes raising questions of Union law
1. Where a dispute submitted to arbitration raises a question of interpretation or application of a concept of Union law contained in this Agreement or any supplementing agreement, or of a provision of Union law referred to in this Agreement or any supplementing agreement, the arbitration tribunal shall not decide on any such question. In such case, it shall request the Court of Justice of the European Union to give a ruling on the question. The Court of Justice of the European Union shall have jurisdiction to give such a ruling which shall be binding on the arbitration tribunal.
2. The arbitration tribunal shall make the request referred to in the first subparagraph after having heard the parties.
3. Without prejudice to the first sentence of paragraph 1, if the Union or the United Kingdom considers that a request in accordance with paragraph 1 is to be made, it may make submissions to the arbitration tribunal to that effect. In such case, the arbitration tribunal shall submit the request in accordance with paragraph 1.
4. In the cases referred to in paragraphs 1 and 2, the time limits laid down in Article INST.17 [Ruling of the arbitration tribunal] shall be suspended until the Court of Justice of the European Union has given its ruling. The arbitration tribunal shall not be required to give its ruling in less than 60 days from the date on which the Court of Justice of the European Union has given its ruling.
5. The provisions of Union law governing procedures before the Court of Justice of the European Union in accordance with Article 267 TFEU shall apply mutatis mutandis to requests for a ruling of the Court of Justice made pursuant to this Chapter.
6. In cases brought before the Court of Justice of the European Union in accordance with paragraph 1, the United Kingdom may participate in the proceedings before the Court of Justice of the European Union. Lawyers authorised to practice before the courts or tribunals of the United Kingdom shall be entitled to represent or assist the United Kingdom in such proceedings.
I would guess the UK will reject this, as least as it relates to trade disputes, and there will be no room for negotiation. But we'll see.
Putting that aside, I'm puzzled by why the EU thinks it needs a principle such as this one in the context of trade disputes. (The UK-EU agreement would deal with other issues as well, and perhaps it makes more sense in other areas). It seems to me that in the trade context, WTO panels and the Appellate Body have generally done a good job addressing questions of interpretation or application of measures that have been challenged, so I'm not sure why the EU's proposed approach would be needed. I also wonder if the EU would be willing to have this principle be used by its trading partners as well (i.e., the partners could provide interpretations of their own measures). If so, the EU needs to make the case for why its approach is better than the current one.