...treaty it would prefer to violate. That, indeed, is how collisions of treaty obligations work; it is ultimately a consequence of the largely uncoordinated nature of international law, a system of subjective rights held against one another by differing groups of subjects of law. Why, to come back to the example, would the US lose its claim to have
Jens Soering extradited, only because the UK had undertaken conflicting obligations vis-à-vis someone else? Conversely, why would Mr. Soering - and the other parties to the ECHR - lose their rights...