Abstract.It is argued that accepting that there are human rights, or that there are categorically binding requirements of any kind on action, logically requires accepting thePGC (Principle of Generic Consistency) as the supreme criterion of practical reasonableness.Consequently,alllegal systems that recognise human rights (hence, the English legal system),allwho view law as a matter of obligation, andallwho consider that there are categorically binding requirements on action, must take thePGCto be a necessary criterion of legal validity. Conventions on human rights must, as conventions onhuman rights, be interpreted to conform with thePGC.