Yes, but it is how law generally, and international law in particular, develops.  Treaties and Legislation are a process of formalising a consensus which forms through custom and practice.  There was and is nothing in law to prevent a country leaving the EU - except the opprobrium of its peers - and whatever influence they can bring to bear.  As always, power is the hidden hand behind many legal processes, balanced only by the fact that a law applied to the weak must (in theory) also be applied to the powerful.  Hence if the US legitimises  torture - the international community cannot really stop it.  What will stop it is a belated realisation in the US is that what goes around, comes around, and it will be in a much more difficult for the US to protect its citizens from torture elsewhere in the future.

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