We typically have rights to do things such as to pick up a bill we find lying on the ground or to sit on an unoccupied bench in the park. We have a right to do so in the sense that we are at liberty to do so; that is, we have no duty not to do these things. Hohfeld’s term was “privilege,” and theorists commonly talk of “a liberty” or “a Hohfeldian liberty” or sometimes “a liberty right.” When we assert a right to do something such as sit on a bench, we often are expressing a Hohfeldian privilege, the first of four “elements” that he introduced to our vocabulary.

One can have privileges or liberties, it is important to note, in the absence of any duties. Indeed, in a world with no duties, everyone would have a liberty or liberty right to do anything. As Thomas Hobbes argued, such a world would be quite awful. (This is Hobbes’s “state of nature,” the natural condition of humankind, prior to the development of a state. See Hobbes 1991/1651, ch. 13.) Some other rights, however, are connected to duties, and it is especially these that “enable and constrain” in the way indicated earlier. These rights are usually called “claim rights” and entail a correlative duty on the part of others. They are standardly understood thus: one person has a claim right against another if and only if the second has a duty or obligation to the first. For example, a lender has a claim right against another that he repay his loan at an indicated time, or we all have a right that others not injure us in certain ways. In both cases the right is correlated with a duty on the part of the other individual (to repay the loan, not to injure). More completely: person A has a claim right to ___ against person B if and only if B has a duty to A regarding ___ (A has a liberty to do ___ if and only if A has no duty not to do ___).

Someone with a claim right to do something is “enabled” in some way or “protected,” and the corresponding person(s) with a duty are constrained. Having bought a ticket to see the movie, one has a claim right to see it, and others have a duty to make this possible. Unlike the unoccupied park bench that I have a liberty to use, I may not sit on the chair on your front porch without your permission.

In a world with no duties, there are no claim rights. In such a world we would lack important protections, as others would have liberties to do whatever they wished to us. The introduction of claim rights and duties would be a significant change, enabling us to do many things we could not otherwise do, protecting our interests and liberties.

This notion of a power is crucial for understanding many legal and political relations, especially authority. A person’s or a body’s authority to create law is a power, one that changes what subjects may do or claim. It is impossible to understand political or legal authority without this notion of a power. The right to rule, claimed by monarchs, parliaments and peoples, is in large part a power to create or to modify the claim rights, liberties and duties of those subject to its rule. The “the right to marry,” for instance, is also in large part a power, one that enables two people to enter into a complex relationship with various claim rights, duties and responsibilities. To deny some—e.g., homosexuals—the right to marry is to deny them a power accorded to heterosexuals; more precisely, it is to construe the right to marry as the power to marry a person of the opposite sex only.

Technically, a power is to be characterized as follows: a person has a power if and only if he or she has the capacity to alter the claim rights or duties of others, including his or her own. A power is a second-order capacity. It is a capacity to alter other jural relations. The point is easily grasped by thinking of rules or norms that give people claim rights and duties. These are what the important British jurist H. L. A. Hart called “primary rules.” These rules may be changed in accordance with “secondary rules,” those that indicate how changes may be made. According to Hart, a developed legal system will consist of both primary and secondary rules (Hart 1994/1961, ch. V). Agents who are enabled by the secondary rules to alter the primary ones have a power, and this power is a second-order capacity to change the first-order rules. Powers can, of course, be third order as well; for instance, in a hierarchical organization or system such as a corporation or the military, superiors may alter the powers of subordinates.

If someone may not have his claim rights or duties altered by others, then he possesses an “immunity,” the fourth of Hohfeld’s elements. One way of “protecting” a right within a political or legal system is by giving bearers immunities with regard to it. Our right to free speech may be in part an immunity; the legislature lacks the power to alter it.

These are the elements of the analysis that Hohfeld originally developed and which many have adopted and expanded. (Many sources offer further explanation of Hohfeld’s categories. A good place to start is Wenar 2011.) They are the main elements we need in order to clarify the different kinds of rights that we have and to raise the questions we need to consider if we are interested in understanding the nature and functions of rights in political and legal systems. I said earlier that rights constrain and enable. How do they do this? In a number of ways. The first and simplest way of constraining someone is by imposing a duty. Such a duty, correlated with a claim right, enables the bearer of the latter to do things. My right to be paid by my employer enables me to obtain goods and services, to plan and the like. We might say that claim rights offer protection. A claim right to liberty, for instance, may protect the bearer’s choices; others have duties not to interfere with them. Or it may protect the bearer’s interests; others have duties to safeguard and to preserve the bearer’s liberty. (Many contemporary theorists distinguish between choice- and interest-protecting accounts of rights. But it is not clear why rights could not protect both interests and liberty.)

How do rights protect? As I said, they constrain. How do they do this? In the first instance by imposing duties. (They can also protect by imposing liabilities, which I have not discussed.) Duties that require action or forbearance constrain people. Suppose I have borrowed a sum and am obligated to repay it on a certain date. Then, at that time, I may not use that money for other purposes and must turn it over to its owner. Suppose I need a car and that you have one that I covet. If you will not lend or give it to me, I may not use it. People tempted to take the lives of others may not do so, barring the normal excusing or justifying circumstances (e.g., self-defense).

How exactly do duties constrain? They forbid or require action; that much is clear. But how do they compel those subject to duties to comply? This is an important question, one that is central to the other questions we are raising. A duty is a requirement, an instruction one must follow. But the modal terms here are not causal. It is hard to refrain from “complying” with the laws of gravity after falling off of a ladder. This way of putting the point is humorous, as there is no question of voluntary compliance. The laws of falling bodies are not normative laws like those of a legal system or of morality; they are causal regularities that apply to material bodies like ours, independently of our wills. When the rule of a moral or legal system applies to us, we usually can disregard or disobey it; we are normally able to do so, but we choose not to. These laws are normative and can be violated. Causal laws cannot be disregarded or violated.

So how do duties constrain? A popular answer is through consequences. Children confronting a directive will sometimes say, “Who’s going to make me?” or “Says who?” The last question raises questions about authority and the source of the directive, as we shall see later. The first raises questions about compliance. Specifically, this question supposes that compliance is assured typically by force of some kind; people are made to comply. Suppose this is right. Then rights protect when duties are enforced.

There is some truth to this claim; duties do often have to be enforced. Legal systems typically attach sanctions to duty-imposing laws, and people are often cognizant of these. One need only think of parking or speeding laws to appreciate the importance of sanctions; many people are quite casual about compliance when they do not fear penalties. But sanctions and force cannot be the whole story. There are, for one, other consequences of failing to comply with duties. An important one, emphasized in much recent social science, is that people are less likely to cooperate with those who fail to comply with rules and norms imposed by law and society. A person or business that fails to pay its bills or honor its agreements will have a harder time buying needed goods and services. Someone who frequently fails to uphold commitments will cease to be trusted. This will be more or less true depending on circumstances (for instance, whether the violators are easily identified). But it seems clear that many considerations regarding the likely consequence of this violation will often ensure considerable compliance with many duties.

Do duties constrain solely through consequences? An important feature of what we might call consequential