Don't Shoot Me, I'm Only the Piano Player.

Eugene has been kind enough to invite me to blog a bit about a book I’ve written called The Legal Analyst. In the coming days I’ll write about some of the ideas in the book. Today I’ll say something about the rationale for the project (and at the end of this entry I’ll offer a historical comment about the legal implications of selling a piano to a house of ill fame. So there will be something for everyone.).

The book is a kind of user's manual for ideas about the law. The ideas aren’t doctrinal categories like contract and tort. They’re tools for analysis that cut across categories like contract and tort. A lot of the chapters involve economic principles, but many others don’t; there’s a good bit of cognitive psychology, political science, jurisprudence, etc. The result is meant to be useful to lots of people: law students, lawyers, scholars, and laymen with an interest in the legal system (perhaps not a bad description of the readership of this blog).

The style of teaching in the book somewhat resembles the approach of my chess website and books — lots of examples meant to build the reader’s ability to recognize patterns. But since most people aren’t as interested in the intersection between law and chess as I am, I won’t linger on the point!

Let me instead pursue the theory behind the book with a question. How should law school be organized? Isn’t it odd that the first-year curriculum is the same almost everyplace, and that it’s structured as it is? A couple of schools have started to experiment with minor innovation, but there still isn’t much of it. Here’s what I might suggest: a year spent just on analytical methods, another year spent entirely on various forms of rhetoric, and then one year on substantive legal doctrines (some of which would also have been taught along the way during the other two years). Not that every school should do this, but shouldn’t someplace do it? Perhaps you have other ideas of your own. I see no reason to assume that one size fits all. Maybe it’s a stag hunt, which is an idea discussed in the book that I’ll talk about later in the week. Or a case of path dependence.

I said a school might usefully spend the first year on analytical methods. That’s the part of my suggestion that relates to the book. There are, in general, two sorts of things one learns at a law school. You learn lots of legal rules — principles that tell you whether a contract is valid, how to tell murder from manslaughter, etc. And you learn how to use tools for thinking about legal problems — ideas such as the prisoner’s dilemma, or the differences between rules and standards, or the notion of a baseline problem, or the problem of hindsight bias, and so on. Those tools for thought are the more interesting and useful part of a legal education, and the greater share of the fun of it, at least if they're taught properly.

Law school courses could be organized around those tools rather than legal subjects, so that in the first year everyone would take a course on the prisoner’s dilemma or on game theory, a little course on rules and standards, a course on cognitive psychology, and so forth, and in each of those classes one would learn, along the way, a bit about contract law, a bit about tort law, etc. But instead law school is carved up the other way around: by legal topics, not by tools. Maybe there are good reasons for teaching law this way, but a side effect is that most students never get that hang of the tools that ought to be the best payoff of the enterprise. They just hear about them in passing. Maybe any given idea gets mentioned by a teacher sometime, or maybe not; maybe it comes up again later, or maybe it doesn’t.

Anyhow, whether or not it makes sense to carve up legal education by methods rather than substantive subjects, I do think there’s at least a place for a book that does this. I hope so, at any rate, because that’s what I’ve tried to write.

Another problem the book means to address has to do with the gigantic volume of legal scholarship churned out every year by law professors. The one percent of it that would be of most interest to a student or to a generalist lawyer or law professor — the portion that amounts to a helpful analytical tool, or to a charming illustration of the use of one — is not so easily found. I’ve tried to round up as much of that one percent as I can (I’ve left out a lot of it, of course), and to explain it as accessibly as possible.

In some cases I’ve enlisted the help of other professors who already had written outstanding explanations of the issues I wanted to cover. The chapter on slippery slopes, for example, is co-authored with Eugene, and really is nothing but an adaptation of his scholarly work on the subject. I’m very grateful to him and to my other co-authors for helping out, and hope that in return I may bring their ideas to some people who might not have heard about them otherwise.

Tomorrow I’ll start talking about some of the ideas in the book, but enough about it for today. As long as I’m here, though, I’ll venture a comment on an issue Eugene raised last week: tort and criminal liability for supplying someone with the means to commit a crime. Eugene didn’t mention another interesting angle on the problem, namely the contractual side. A contract to help someone commit a crime is unenforceable. A very classic example is the old English case of Appleton v. Campbell, [1826] 2 C & P 347. It mustn’t be paraphrased; only direct quotation will do:

Assumpsit for board and lodging. The defence was, that the defendant was an immodest woman, and used the lodging for the purposes of prostitution, to the knowledge of the plaintiff.

To substantiate this, another female, who lodged in the house, and who was called for the plaintiff, proved, on her cross-examination, that the defendant was in the habit of receiving male visitors, and that the plaintiff used sometimes to open the door for them; and that the plaintiff told her, that the defendant was an immodest woman.

Abbott, C.J. — If a person lets a lodging to a woman, to enable her to consort with the other sex, and for the purposes of prostitution, he cannot recover for the lodging so supplied. But if the defendant had her lodgings there, and received her visitors elsewhere, the plaintiff may recover, although she be a woman of the town, because persons of that description must have a place to lay their heads; but if this place was used for immoral purposes, the plaintiff cannot recover.

There is a distinctively American version of this problem, too, from when the world was young: someone sells a piano to a house of ill fame, and the proprietor of the establishment defaults on the obligation to pay for it. Is the contract enforceable? The case raises nice questions about the relationship between the piano playing in a brothel and the other activities carried out there. (Not long ago Robert Hughes said, “One gets tired of the role critics are supposed to have in this culture: It's like being the piano player in a whorehouse; you don't have any control over the action going on upstairs.”)

This precise issue doesn’t generate much litigation now, probably (I claim no expertise) because no modern brothel can be bothered to hire a piano player, or for that matter a player piano — unless, I suppose, it’s going for retro charm, sort of like Camden Yards. But once upon a time there was a fun if minor division of authority on this little problem of pianos. See Hollenberg Music Co. v. Berry, 106 S.W. 1172 (Ark. 1907); Colburn v. Coburn, 211 S.W. 248 (Tex. Civ. App. 1919).

The Stag Hunt.

The Legal Analyst has a section on cooperation and other problems for groups. Some of the chapters in that section involve game theory, and one of them covers the game known as the stag hunt. Let me explain it here. It’s fun to think about, and I’ve found that it’s less well-known than the prisoner’s dilemma (which is also discussed in the book, of course).

The two of us are hunters. If we cooperate we can take down a stag and have it for dinner; if we work alone, we’ll only be eating hare. My hope, of course, is that we’ll cooperate and eat stag. But I wouldn’t want to hunt stag if you don’t; that’s my last choice. It will be a waste of time and leave me hungry. Of course you don’t want to go after stag, either, unless you’re sure I will, too.

So maybe we can agree to work jointly and have a stag hunt, but there is risk in it. Unless we have good reason to trust each other, the temptation will be great for either of us to give up on the stag and give chase to any hare that goes by. At least if I do get a hare I no longer have to worry that I’ll end up with nothing if you decide to go after a hare because you think it’s good insurance against the danger that I’ll go after a hare because I’m worried that—and so forth.

We owe this parable to Rousseau’s Discourse on the Origin and Basis of Inequality among Men. There are many situations like this where players in a drama do best by all cooperating, but otherwise had better all defect; if they don’t all cooperate (or if some critical mass won't cooperate), in other words, then nobody should — so perhaps nobody does. A mutiny can be another simple example, or (more vividly in our times) efforts to overpower hijackers on an airplane.

The stag hunt may remind some readers of the prisoner’s dilemma, but it works differently. In a prisoner’s dilemma it’s best for you to defect no matter what I do. In a stag hunt that’s not true; if I know you will cooperate, I’ll want to cooperate, too. Sometimes a stag hunt is said to be an assurance game because that is the true issue: if everyone has good assurances that everyone else will cooperate, they will be glad to do the same.

For understanding these games, the idea of a Nash equilibrium helps. The players of any game have arrived at a Nash equilibrium if, given what everyone else is doing, none can do better by changing their strategies. Sometimes there is more than one equilibrium the parties can reach, and a stag hunt is an example of this. Do you see why?

Eating hare is an equilibrium. If we take as given that you’re eating hare, there’s no sense in my getting up to chase stag; if we take as given that I’m eating hare, there is no point in your chasing stag, either. The situation is unappetizing but stable. We all could do better by changing, but it wouldn’t be rational for either one of us to be the first. So we just keep eating hare. Yet hunting stag also is an equilibrium if we somehow can get there. Once we’re doing it — once we’re cooperating confidently — there’s no reason for anyone to go back to having hare.

Efforts to solve stag hunts, like the problem of rent seeking discussed yesterday, help to explain some laws and legal doctrines; examples are discussed in the book, and include deposit insurance for banks, “circuit breakers” in stock markets, some cases of neighborhood segregation, and maybe even some of the rules about when judges are supposed to interview and hire law clerks. The value of understanding the stag hunt (or any game) is that it allows you to perceive common patterns in situations like these. That's interesting in itself, and it also can then help you make sense out of new problems that aren't solved yet and just look like an uncooperative mess.

Perhaps you can suggest some other “stag hunt” situations that law is used to address (sometimes the tricky part is separating these from the prisoner's dilemmas, where your first ("rational") choice is for everyone to cooperate except you; those tend to be more common than stag hunts and to call for different sorts of solutions). Or maybe you would enjoy speculating about some situations that might be stag hunts might not be. Part of what makes a stag hunt interesting is figuring out why the game works that way — in other words, what makes people reluctant to do X unless others do it, too. Why are some people so much more willing to support redistributive tax policies that bind everyone than they are to just voluntarily write checks that redistribute their own income to others? Why did so many hockey players resist wearing helmets until it was made a rule? Etc.

Puzzles About Proof.

I have a taste for conundrums and paradoxes, and The Legal Analyst discusses lots of them. Here are a couple of fun examples involving problems of proof:

1. The conjunction paradox. The standard of proof in a civil lawsuit — a case arising from a car crash, for example — is the preponderance of the evidence: the plaintiff has to prove his case by a “more likely than not” standard. So imagine a case where there are three contested issues. Maybe it’s an accident case where the plaintiff has to prove (a) that the defendant was negligent, (b) that the negligence was the cause of the accident, and (c) that he has a good, truthful excuse for the fact that the claim appeared to be late under the statute of limitations. The jurors decide that they are around 60% sure that the plaintiff is right about the negligence claim, around 60% sure that he is right about causation, and around 60% sure that he is truthful in his story about the statute of limitations.

Should the plaintiff win this case? (Don’t be too sure of yourself!) Would the plaintiff win this case? In other words, how do you think the jury should and would be instructed to act if it reached these conclusions?

[UPDATE. The plaintiff will probably win, because jurors generally are told to find for the plaintiff so long as they think each element of the case is proven by a preponderance of the evidence. Yet the chance that all of the elements of the plaintiff's case are true is around 22%, which seems to flunk the preponderance standard, creating not only a paradox but some potentially serious problems of policy.

There are various replies to this — that sometimes these probabilities may not be independent, or that sometimes the jury may be choosing between only two possible stories, or that we can draw additional confidence from the fact that (say) six jurors, and not just one, all reached the same conclusions. But many students of the paradox nevertheless conclude that defendants are often held liable when they shouldn't be. See, e.g., Ronald J. Allen and Sarah A. Jehl, Burdens of Persuasion in Civil Cases: Algorithms v. Explanations, 2003 Mich. St. L. Rev. 893. These ideas are discussed more in the book.]

2. Proving the law. Suppose you offer to trade a gun to a drug dealer for a couple of ounces of cocaine. The seller accepts, then announces that he is an undercover FBI agent and leads you off to jail. You are prosecuted under a statute that gives many years of prison to anyone who “uses" a firearm in relation to a drug trafficking offense.

You have two lines of defense. You plan to deny that you ever really offered the gun to the undercover agent; to overcome this denial, the government will have to prove its case beyond a reasonable doubt. So far, so good. But you also have another argument: that the prosecution has misread the statute. You don't “use” a gun if you try to barter it; you only "use" a gun (you plan to argue) by putting it to work as a weapon.

There are lively arguments to make either way on this issue (and I’m not really looking for them here). Assume that the judge thinks it’s close but decides that the statute does cover your case. Well, but wait — how sure must the judge be? Is it necessary that he be convinced beyond a reasonable doubt? If not, why not? (I consider the second question — why — the more difficult and interesting part.)

[UPDATE. The puzzle is that we require a very high level of certainty when it comes to facts in criminal cases, but not when it comes to law; we are willing to award long prison sentences, or for that matter death sentences, on the basis of interpretative decisions that everyone knows may be quite doubtful. Indeed, judges do not generally confess to using any standard of proof or confidence at all when they interpret the law, with the partial, occasional, and unreliable exception of the rule of lenity (the use of which I discuss here).

The best explanation of this state of affairs, perhaps, is that if we required any particular level of confidence before a judge could state the law, there might be many situations where there ends up being no law because there is no interpretation that satisfies the standard of proof. This could have some rather untoward consequences. These ideas, again, are discussed in the book; the most interesting longer treatments, I think, are Gary Lawson, Proving the Law, 86 Nw. U. L. Rev. 859 (1992); Larry Alexander, Proving the Law: Not Proven, 86 Nw. U. L. Rev. 905 (1992).]

Cascades.

You have job interviews with two employers and are turned down in both of them. At the next one you are asked if you have had any prior interviews. You recount your unhappy recent history and the employer concludes that the two prior rejections probably meant something. This helps him decide to pass on you. The process continues and accelerates from there; the next interviewer finds you have three rejections and has even more cause for concern than the previous one.

This is an example of an information cascade. Notice that all the interviewers might be acting rationally. If you feel uncertain about something, it might make sense to defer to others who have already decided; maybe they knew more than you do. And if the next player likewise has no firm basis for decision it might be entirely reasonable for him to see the growing agreement, find it impressive, and go along. But whether reasonable or not, the result is that the belief gains a kind of empty momentum: there is growth in its acceptance but not in its likelihood of being true, which hasn’t changed and may be small.

There are a number of implications for law. One involves the hazards of sequential decisionmaking. When witnesses are asked what they saw, they say different things alone than if they first hear how others describe the events; there are various ways to interpret this, one of which is that it’s a kind of cascade. That is why the federal guidelines say that witnesses to crimes should be separated and shouldn’t talk to each other.

A similar problem arises when jurors vote on a case. Should they vote simultaneously or sequentially? A simultaneous vote has the advantage of avoiding cascades: we don’t want the third juror swayed by what the first two say, then the fourth juror swayed by what the first three say, and so on. So the choice of procedure might matter; oddly, though, we leave it up to each jury to decide what to do. The same general question arises again when judges vote. On the United States Supreme Court the Justices vote openly and one at a time, starting with the Chief Justice and then descending to the most junior member, who already knows how all the other Justices voted when his turn arrives -- suggesting a danger of cascades.

The risk of cascades repeats on a larger scale in elections. Think about cascades created by early primaries, for example, or by public opinion polls (which is why some countries ban them in the days or weeks before an election). Might a cascade also arise when courts in different jurisdictions are presented with the same question, one after the other? There are other interesting kinds of cascades, too, but this entry is getting long; so if you’d like to read about them (or more about the kind just described), they are the subject of one of the sample chapters available at the web site.

This post wraps up my guest-blogging for the week. I hope these discussions have piqued the interest of some of you in The Legal Analyst. The sample chapter just mentioned, and the others at the web site, should give you a clearer idea of whether the book is for you (they go into more detail than I’ve had space to do here); and there will soon be a fourth sample chapter available at Eugene’s own site — the chapter on slippery slopes, which, as I mentioned before, I co-wrote with Eugene but is really just a short adaptation of his classic article on the subject. Thanks so much to Eugene and the other writers at his site for having me here, and to the many readers who have sent me suggestions or posted them to the comment threads.