It was exceptional for the King to sit on the Court of the King's Bench, which worked independently of the King and became confined to the established common law.
The Court of Common Pleas had three types of jurisdiction: 1) common law jurisdiction between person and person, including actions regarding land, which was exclusive, 2) personal actions of debt, detinue, account and covenant, and 3) mixed actions, both personal and regarding land, e.g. ejectment. It had shared jurisdiction with the Court of the King's Bench in maintenance, conspiracy, other breaches of statute, trespass, trespass on the case, and their derivatives. Most of its business had to do with recovery of debt, from 40s. to thousands of pounds. The King's Bench and Common Pleas courts vied with each other for cases in order to get more profits of justice.
Grand juries were summoned by the sheriff to decide whether, on the evidence of the prosecution, there was a case to go to trial. The petty or trial jury heard all parties to a lawsuit and determined the facts. In 1351 a statute required that no member of a grand jury could sit on a petty jury if so challenged by the accused.
Decisions of the common law courts are appealable to the House of Lords. The king's council members who are not peers, in particular the justices and the Masters of the Chancery, are summoned by the House of Lords only as mere assistants. Parliament may change the common law by statute. The right of a peer to be tried for capital crimes by a court composed of his peers was established. There was a widespread belief that all the peers are by right the king's councilors.
No attorney may practice law and also be a Justice of Assize. No justice may take any gift except from the king nor give counsel to any litigant before him.
In 1390, there was a statute against maintainers, instigators, barretors, procurers, and embracers of quarrels and inquests because of great and outrageous oppressions of parties in court. Because this encouraged maintenance by the retinue of lords with fees, robes, and other liveries, such maintainers were to be put out of their lords' service, and could not be retained by another lord. No one was to give livery to anyone else, except household members and those retained for life for peace or for war. Justices of the Peace were authorized to inquire about yeomen, or other of lower estate than squire, bearing livery of any lord.
Whereas it is contained in the Magna Carta that none shall be imprisoned nor put out of his freehold, nor of his franchises nor free custom, unless it be by the law of the land; it is established that from henceforth none shall be taken by petition or suggestion made to the king unless by indictment of good and lawful people of the same neighborhood where such deeds be done, in due manner, or by process made by writ original at the common law; nor that none be out of his franchise, nor of his freeholds, unless he be duly brought into answer and before judges of the same by the course of law.
The Chancery came to have a separate and independent equitable jurisdiction. It heard petitions of misconduct of government officials or of powerful oppressors, fraud, accident, abuse of trust, wardship of infants, dower, and rent charges. Because the common law and its procedures had become technical and rigid, the Chancery was given equity jurisdiction by statute in 1285. King Edward III proclaimed that petitions for remedies that the common law didn't cover be addressed to the Chancellor, who was not bound by established law, but could do equity. In Chancery, if there is a case that is similar to a case for which there is a writ, but is not in technical conformity with the requirements of the common law for a remedy, then a new writ may be made for that case by the Chancellor. These were "actions on the case". Also, Parliament may create new remedies. There were so many cases that were similar to a case with no remedy specified in the common law, that litigants were flowing into the Chancery. The Chancellor gave swift and equitable relief, which was summary. The Chancery Court had no jury. With the backing of the council, the Chancellor made decisions implementing the policy of the Statute of Laborers. Most of these concerned occupational competency, for instance negligent activity of carriers, builders, shepherds, doctors, cloth workers, smiths, innkeepers, and gaolers. For instance, the common law action of detinue could force return of cloth bailed for fulling or sheep bailed for pasturing, but could not address damages due to faulty work. The Chancellor addressed issues of loss of wool, dead lambs, and damaged sheep, as well as dead sheep. He imposed a legal duty on innkeepers to prevent injury or damage to a patron or his goods from third parties. A dog bite or other damage by a dog known by its owner to be vicious was made a more serious offense than general damage by any dog. A person starting a fire was given a duty to prevent the fire from damaging property of others. The King will fine instead of seize the land of his tenants who sell or alienate their land, such fine to be determined by the Chancellor by due process. The Chancery is now a court side by side with the common law courts of Common Pleas, King's Bench, and Exchequer.
Only barons who were peers of the House of Lords were entitled to trial in the House of Lords. In practice, however, this pertained only to major crimes.
Treason was tried by the lords in Parliament, by bill of "attainder". It was often used for political purposes. Most attainders were reversed as a term of peace made between competing factions.