Bentham was a political thinker and a policy entrepreneur. Bentham wanted to see England reform all its laws, he wanted to see Parliament write lots of statute to make the law through statutes and to get rid of the common law. And he proposed this more forcefully and comprehensively in his 1802 book, A Theory of Legislation than anywhere else. To get his reform project going though, Bentham needed to call the common law into question. He did that in a work called A Fragment on Government, which he published in 1776. Blackstone penned his commentaries from 1766 to 1769. In A Fragment on Government, Bentham started where Blackstone started. Bentham took Blackstone's definition of law as a rule of civil conduct made by the supreme power, commanding what's right and prohibiting what's wrong; and he took Blackstone's mention that things like laws that are not consistent with the natural law have no validity. In a treatment of a crime, Blackstone had assumed in passing that the laws of England were just in most or all particulars, and Bentham took all those passages of Blackstone together, and criticized Blackstone. Bentham argued that Blackstone's account of law was too conservative. It tended to conserve in place the law that was in effect, and he took the quote from the fourth book of Blackstone's Commentaries to say Blackstone was assuming all of English law was just as it was. Bentham drew the inference that Blackstone would object to there being any change to the law if all the laws of England were just as they were, and any change would make them unjust, and any law that's unjust has no validity, then there was no way for reformers in parliament to reform the common law to make it better. And so Bentham criticized Blackstone. He thought that it was preposterous for Blackstone to say that all the laws of England were just. He thought it was preposterous for Blackstone to say that laws do not have validity in positive law unless they are just consistent with the natural law. Bentham used that critique then to introduce an important distinction. Bentham criticized Blackstone for running together two different ways someone might look at law. One of those was the view of the censor, and the other was the view of the expositor. The expositor is the person who wants to know what the law is. The expositor doesn't care whether the law is a good law or bad law, he just wants to know what the law is. The censor is the person who thinks, has strong opinions about what the law ought to be, and the censor takes whatever the account is of what the law is, and then says that's a good law or a bad law. And if it's a bad law, the censor then proposes a reform. The natural law account makes custom seem a kind of law. And common law is a kind of custom. It's law that's been discovered by judges, and the grounds for the discovery are two; that a principle seems reasonable, consistent with natural law; and a particular practice that seems reasonable in this way has been followed for a long period of time by a lot of different lawyers all working together. And if it seems natural, sorry for the repetition to move from morality to judge-discovered law this way, one doesn't need a lot of law made by legislatures. If one thinks that people need to make a lot of arbitrary choices when they take principles of morality and apply them, one needs legislatures to do a lot more work than Blackstone seems to give credit for.