I am grateful to the noble Lord for canvassing that. Again, I accept that it is an important point, as are all those that have been made around your Lordships’ House today.
Not all principles of international law are tested before a court, and acceptance by the international community of a particular practice, or codification by relevant institutions, as in the articles on state responsibility, can provide very significant precedent. Necessity provides a justification for non-performance with specific terms of the protocol, for as long as the circumstances justifying necessity persist. That relates to the temporal point which the noble Lord makes. The relevant circumstances could last for a significant length of time, so it is not necessarily a short-term justification.