This chapter shows that Bentham's ideas on deontic logic, the logic of legal defeasibilityand the logic of derogation represented very illuminating contributions to the theory of law. Deontic logic is a branch of logic which deals with normative concepts as obligatory, forbidden, permitted or optional normative systems and normative reasoning. The new edition of Bentham's most important work on legal theory stresses the originality and freshness of the Benthamite account. For Bentham, non-commands and permissions are de-obligatory laws, which only take effect where the primordial law or any determinate part of it is destroyed, declare it repealed and throw it out of the code. The fact that the manuscript remained undiscovered until Professor Charles Warren Everett found it among Bentham's manuscripts at University College London in 1939 is only another of the veils of mystery of Jeremy Bentham.