A "liberty" (Latin libertatis or freedom) in the king's courts of medieval Europe usually referred something very different than it refers to now. It referred to the right of someone to deprive some other people of some of their normal rights as law-abiding subjects. In other words, it referred to a political property, a specifically limited right to coerce some set of people, usually for law enforcement or military or other political purposes. This curious meaning, in some ways quite the opposite of our modern meaning, reflects the conundrum that one person may use some freedoms to deprive another person of their freedoms. To prevent this, these "positive" freedoms to coerce can be limited to procedural powers by which are enforced substantive laws that are generally non-coercive, i.e. that generally protect only "negative" rights. English-derived common law (i.e. law in Great Britain, the Commonwealth, the United States, etc.) since at least the sixteenth century has generally accomplished this, and as we shall see it has used the flexibility of vague phrases to evolve a variety of modern negative rights.
Medieval positive liberties that could be owned included the right of a lord to hang thieves caught red-handed in his territory, the right to hold a market and run a law-merchant court, to collect taxes for the king or for oneself, to be a privateer (i.e. a pirate legitimized under the king's laws), to conquer and run a foreign territory, and so on. There were many dozens of kinds of these political properties specified in thousands of property deeds, called charters. Charters often freely bundled real property (i.e. land) with a variety of political properties over territories matching the boundaries of the real property, but on occasion political properties could be unbundled from land, and specific kinds of political property could be combined with each other in a dizzying variety of ways. Political properties could be held by individuals (as in lords of the manor, counties Palatine, the proprietary American Colonies, and many other examples) or corporations (guilds, boroughs, cities like London and York, companies like the East India Company, the corporate American colonies, and so on).
Individually owned politcal properties were generally hereditary. The king exercised his own hereditary political property, called the Realm or the Crown, from which at least in theory all other political property rights had been originally granted. As the original grantor the king retained via his courts jurisdiction over disputes involving those coercive properties, via the extraordnary or prerogative writs. Most political property rights only involved certain narrow subsets of the royal political powers, while some (such as the county Palatine) were very broad, including all royal powers within the boundaries of the county subject only to the intrusion of the king's extraordinary writs.
In the foreign relations context, in the granting of powers of naval warfare, piracy, and colonization, political property was used for offense as much as for defense. In the domestic context, justice was meted out by these privately owned courts more often than injustice, but it should be observed that breaking free of the jurisdiction of the local lord in order to come under the jurisdiction of the king was, more than any other event, referred to as gaining one's "freedom". If you were the subject of a lord as well as, mostly indirectly, of the king, you were "unfree". If you were the subject of only the king and his ministers, you were "free". At least that is how the king's courts and ministers and any newspapermen that didn't want to be imprisoned for libel by the king's courts referred to it.
In their quest to usurp the political properties of the lords, boroughs, cities, and guilds to run their local courts, the king's courts used cases brought under the extraordinary writs to evolve a set of "liberties" with a different meaning: liberties the way most of us think of them, negative liberties that individuals held against these private law enforcers as subjects of the king, and thus justified removal of the cases to the king's courts. The definitions of various political properties increasingly included the procedures within which those rights to coerce had to be exercsed in order to protect the king's subjects from injustice. Thus we see, for example, over the sixteenth to eighteenth centuries the king's courts successively stripping guilds of various of their jurisdictional powers and thereby increasing the liberty of the individual to freely engage in their trade. To try to be consistent, the king's judges also often, though by no means always, respected these negative liberties themselves in order to justify by rules their usurpation of the positive liberties of rival private courts.
Many of the basic constitutional rights of individuals, for example of the rights enshrined in the U.S. Bill of Rights, descend from these efforts. The lex mercatoria evolved in the privately owned market courts of Western Europe. Much of this merchant law was later incorporated into the common law (the law of the king's courts) in Great Britain by merchant juries in the century leading up to the industrial revolution. At the same time, the king's courts gained a large degree of independence from both the king and the rising power of Parliament, forming a separation of powers between the executive, legislative, and judicial branches that was to be used as a model for the United States Constitution.
Lord Coke, Chief Justice of the king's court of Common Pleas under King James I in the early seventeenth century, declared in Dr. Bonham's Case that these common law rights could even limit the power of Parliament, but this argument came to be neglected by later courts. There has been longstanding debate over whether this argument of Coke's was a legally binding "holding" necessary to reach the verdict of the case or an unecessary "dictum" and thus not binding precedent. A similar doctrine was, however, revived in the United States based on interpreting broad statements in our Constitution such as "due process" in terms of rights derived from English common law in order to limit the powers of Congress and the President. The term "due process" comes from a series of charters that followed the Great Charter (Magna Carta). The phrase was considered largely synonymous with "the law of the land" that features in the Magna Carta, and referred to procedural rights, including the rights of political property and procedural limitations on those rights, that were considred the "common law" at that time. However the United States' courts' much later interpretation of the phrase has been far more creative and modern, including the oxymoronic phrase "substantive due process" under which rights to freedom of contract, school choice, birth control, and abortion, among other such negative personal rights, have been unearthed and applied to limit State and Federal legislative and executive powers. (More on the history of due process here). The modern British Parliament, on the other hand, is considered to have arbitrary sovereign powers, which can only be limited in certain cases by interpreting the language of its statutes in narrow ways to conform with the unwritten British constitution, i.e. its procedural common law traditions, but again with many creative modern flourishes.
In their efforts to limit locally coercive liberties by enhancing negative liberties, the king's courts fell short of consistency in some important ways. For example, a liberty of a corporation to enforce its regulations about a given subject matter (e.g. medicine, for a medical guild) in a given territory was often stripped from that corporation in a case involving a dispute between an individual and that corporation (e.g. somebody practicing medicine in the territory without permission of the guild), on the theory that "one should not be a judge in his own case." This is a very sound principle, and in the case of the guilds it led to the rise of free trade, but as the corporate barristers were quick to point out, the king's courts often did not apply this principle to themselves -- cases involving the king, which were many, remained in the king's courts. To some extent this was achieved by the independence of the king's courts, but it did not prevent these courts from gradually usurping the political property of the private courts and other privately held legal institutions and, with the generous help of Parliament and its own will to power, eventually extirpating them.
There is a detailed analysis of many English cases involving privately owned rights to hold courts and enforce laws, including Dr. Bonham's Case, in my paper Jurisdiction as Property.