My opinion is that EU Regulations are not subject to the VCLT as a treaty, but the CJEU selectively applies VCLT rules that reflect customary international law as part of the EU's constitutional commitment to respect international law under Article 3(5) TEU.

Thank you David Norman

It is a very good point.

I think that an interesting issue in particular is the relationship of the VCLT to the so-called "secondary EU law".

I believe the Vienna Convention on the Law of Treaties (VCLT) generally applies to international treaties between states. However, when it comes to EU Regulations, the situation is a bit different.

EU Regulations are a form of EU law, and they are directly applicable within member states without needing to be transposed into national law. The VCLT, which governs the interpretation and formation of treaties between states, doesn't directly apply to EU Regulations because EU law has its own set of rules and governing principles.

However, some aspects of the VCLT, like treaty interpretation, can still influence how EU regulations are understood. For example, if the EU enters into an international treaty, the VCLT would guide how that treaty is interpreted, but the regulations themselves are typically a product of EU internal law and not subject to the VCLT in the same way state-to-state treaties would be.

In simpler terms, think of the VCLT as the rulebook for treaties between countries, while EU Regulations are more like the rules within the EU for its members. They work within their own systems, but there might still be a bit of overlap when the EU is dealing with external treaties.

Thank you Aftab Haider

This is a very interesting observation.

EU Regulations are directly addressed to the Member States of the EU. The act is adopted by a body at international (european) level to (for) a body (state) at national level. Does the EU Member State law play any role in the execution of such an act (EU Regulation)? How do you think?

لا تُطبَّق اتفاقية فيينا مباشرةً على "لوائح الاتحاد الأوروبي" (EU Regulations)، لأنها ليست معاهدات بين الدول، بل هي تشريعات داخلية صادرة عن مؤسسات الاتحاد الأوروبي، وتخضع لقانون الاتحاد الأوروبي نفسه، وليس للقانون الدولي العام.

The Vienna Convention on the Law of Treaties (VCLT, 1969) does not directly apply to EU Regulations, since it governs written treaties between sovereign States (and under Article 5 VCLT only applies to treaties between States and international organisations in a limited way)—and EU Regulations are internal secondary legislation, not treaties signed by sovereign States. Nonetheless, the Court of Justice of the EU (CJEU) consistently treats many provisions of the VCLT—particularly Articles 31–33 on interpretation, Article 29 on territorial scope, Article 34 on pacta tertiis, and Article 60 on material breach—as reflecting customary international law, and applies them indirectly to the interpretation and implementation of international agreements concluded by the EU and, by extension, to give effect to EU secondary law in conformity with those customary rules. In my view, the correct legal position is that VCLT does not bind EU Regulations as such; rather, its provisions serve as authoritative interpretive guides to customary treaty‑law norms that inform both the interpretation of international treaties concluded by the EU and the alignment of EU secondary legislation with customary international law.

Vladimír Šefrna Thank you for your input.

Am I correct in understanding that you are also asserting that the provisions of the VCLT constitute rules of customary international law?