This chapter discusses several paradigmatic examples of norms treated defeasibly by common law courts and, on this basis, proposes a challenge for contemporary positivist theories: whether any social sources thesis in general or Hart's Rule of Recognition in particular can accommodate themselves to such endemic defeasibilism in adjudication. It argues that they cannot, ‘for the Rule of Recognition must either strive for greater and greater breadth in order to include all possible sources of override or that the rule of recognition must be understood as identifying some but not all relevant...

This chapter discusses several paradigmatic examples of norms treated defeasibly by common law courts and, on this basis, proposes a challenge for contemporary positivist theories: whether any social sources thesis in general or Hart's Rule of Recognition in particular can accommodate themselves to such endemic defeasibilism in adjudication. It argues that they cannot, ‘for the Rule of Recognition must either strive for greater and greater breadth in order to include all possible sources of override or that the rule of recognition must be understood as identifying some but not all relevant legal materials’.