Legal Systems Very Different from Ours is the latest book by the libertarian economist David Friedman, with a single chapter each contributed by Peter Leeson (on the law of pirates) and David Skarbek (on the law of prison inmates). It describes 13 different legal or quasi-legal systems from a variety of places and times. No modern nation-state is found among these systems, and some readers may decline to count some of the systems as genuine legal systems at all.

This would be particularly true of the "embedded" legal systems—those adopted by a sub-group within a larger society that has its own, government-made law. Pirates, prisoners, gypsies, and the Amish are all subject to traditional governmental law, whether or not they respect it, yet each group also has or had its own code of conduct and methods for enforcing it, which sometimes conflict with the state-made law of the wider society.

All of the systems in the book are nevertheless recognizably law-like. That is, all are systems of socially enforced rules of conduct designed to mitigate and manage human conflict. The book's other examples include imperial Chinese law, Jewish law, Islamic law, saga-period Icelandic law, Somali law, early Irish law, the law of the Plains Indians (Comanche, Kiowa, and Cheyenne), 18th century English law, and ancient Athenian law.

Readers familiar with Friedman's political views may be expecting a defense of an anarcho-capitalist legal system, yet, for better or worse, he holds back on that score

In general, Friedman handles normative questions with a very light hand. At the outset, he lets readers know that all the systems to be considered deserve to be taken seriously, as all are the work of adults no less intelligent than those who designed the modern American legal system. I confess that at certain points, I found it difficult to take some of these "very different" systems seriously as systems of justice. Under imperial Chinese law, for example, "If beating a child resulted in his death and there was no excuse for the beating, the punishment was one year of penal servitude. … There was no punishment for a reasonable beating of a disobedient son that resulted in death." (Emphasis mine.) Reading that, I am inclined to doubt not the intelligence but the moral decency of the people who designed such law. But Friedman describes such seeming outrages dispassionately, without the moralism some of us might be tempted to indulge.

Friedman makes no effort to identify the best system, expressing doubt more than once that any such thing exists. He aims only to understand them, identifying some of the important advantages and disadvantages of each before making a few suggestions for reforming our own legal system. There is a faint libertarian theme which might go unnoticed by those unfamiliar with Friedman's earlier work. Perhaps Friedman was trying to illustrate the feasibility of reducing the legal system's reliance on the state in favor of private mechanisms; nevertheless, the book covers each legal system in general, rather than focusing solely on the aspects that teach libertarian-friendly lessons.

I believe imperial China was chosen chiefly to illustrate the potential for designing contracts that minimize people's need to use the court system to resolve disputes. (This was done by relieving each party of duties whose breach would be difficult to prove.) Several systems were seemingly chosen to illustrate the feasibility of private enforcement of court decisions, in contrast with our own system's entirely government-based enforcement. In saga-period Iceland, for example, courts' decisions were enforced by private violence. If one party to a dispute disobeyed the court's decision, that party could be declared an "outlaw" by the court, with the consequence that it would become legal for other members of the society to kill that individual. This eliminates the need for a centralized, governmental police force, albeit in a brutal manner.

In the case of present-day American prison inmates, individuals join gangs chiefly for protection, and these gangs enforce laws against their own members. If a gang member disrespects a member of a rival gang in a manner deemed unacceptable by prison culture, the offender's own gang may authorize, or themselves carry out, a beating of the offender, with the aim of keeping the peace between gangs. A less violent and more sympathetic example is Amish laws, which are generally enforced by social ostracism.

This book stops short of calling for private enforcement of all laws. Friedman does not hold back, however, when he describes the possibility, under medieval Icelandic law, of a tort victim giving or selling his legal claim to another party. Friedman thinks this a great advantage of the Icelandic system over the modern American system. If, for instance, you have vandalized my house, but I am for some reason unable or unwilling to directly pursue a lawsuit against you, I should be able to give or sell my claim for damages to someone who is more willing and able to pursue the case. Perhaps there would be a company that would pay me for the right to pursue a lawsuit on my behalf; if the lawsuit wins, the company then receives the damages that would have been due to me.

Another improvement Friedman puts forward is inspired by the system of ancient Athens. There, private individuals could prosecute one another for crimes. They would then be tried by a large jury. If the prosecution was successful, the prosecutor would receive a portion of the fine imposed on the defendant. If the prosecutor failed to convince at least 20 percent of the jury of the merits of his case, the prosecutor himself would be fined. This deters meritless accusations.

Along similar lines, Friedman proposes that tort plaintiffs who lose should be required to pay compensation (over and above court costs) to the victorious defendant, with the amount of compensation proportional to the amount that the plaintiff sought to recover from the defendant. In addition, he suggests, government prosecutors who repeatedly file charges for which they cannot convince at least four jurors to vote for conviction should be removed from their jobs. These rules would eliminate incentives to file frivolous lawsuits or unjustified criminal charges.

Taking a page from 18th century English law, Friedman suggests that private citizens should be permitted to initiate criminal prosecutions, but perhaps only against government officials. This would address the problem of the government's unwillingness to prosecute its own members.

On each of these points, I find Friedman's recommendations well-taken. Friedman generally considers costs and benefits in utilitarian terms, asking not "Is this rule intrinsically just?" but "What desirable or undesirable behaviors would this rule bring about?", using the economist's assumption of generally rational and self-interested agents to answer the latter.

As in his earlier work, Friedman occasionally draws striking connections. My favorite example: Courts in the Middle Ages faced a problem with collecting enough evidence for convictions. Their solution was to extract confessions from suspects by means of torture. Similarly, modern-day American prosecutors face difficulties satisfying the demanding standards of trials. They, too, solve this problem via coerced confessions: They threaten to pile up more charges—or more serious charges—against the defendant unless the defendant pleads guilty. Like the medieval approach, this technique works against the guilty and innocent alike. Suppose I have just a 10 percent chance of being convicted at trial, of an offense that comes with an expected 20-year prison sentence. The prosecutor need only offer to reduce the charges against me to something with a less than 2-year sentence, and it becomes rational for me to accept a deal. Of course, my "confession" under such circumstances hardly constitutes strong evidence that I am guilty of anything.

This is just one of many insights sprinkled throughout the text. Friedman's fans will appreciate the book's characteristic clarity, candor, and rationality.