Technical Report Number
Hart's "Ascription of Responsibility and Rights" is where we find perhaps the first clear pronouncement of defeasibility and the technical introduction of the term. The paper has been criticised, disavowed, and never quite fully redeemed. Its lurid history is now being used as an excuse for dismissing the importance of defeasibility.
Quite to the contrary, Hart's introduction of defeasibility has uniformly been regarded as the most agreeable part of the paper. The critics' wish that defeasibility could be better expounded along the lines of a Wittgensteinian game-theoretic semantics has largely been fulfilled.
Even the most contentious part of the paper, Hart's claim that the ascription of acts implies responsibility, is not as mistaken as some have taken it to be.
The paper remains a paragon of clarity in the important and active scholarly area that crosses legal reasoning, language, and logic.
Loui, Ronald P., "Hart's Critics on Defeasible Concepts and Ascriptivism" Report Number: WUCS-95-02 (1995). All Computer Science and Engineering Research.