The exchange below between Eric Posner and Jonathan Adler brings up the classic tension between simple laws and more complicated ones, and I wanted to blog more about it. In the abstract, everyone wants laws that are simple. The ideal is simple and straightforward. But often a single rule must regulate a very wide range of different circumstances, and then you get pressure to be more flexible: Either to enact a very vague standard that isn't clear (like "act reasonably"), or else to start carving out exceptions to the rule for all the specific cases you think need different treatment. The best way forward can be tricky. Put another way, the ideal is for law to be clear, simple, and sensible. But these goals are often in tension.

  To see an example of this, consider the following hypothetical exchange over how much privacy Congress should extend to e-mail. I'll make the exchange between "Complicated Karen" and "Clear Chris," who are both trying to figure out the law of e-mail privacy and what Congress should do. Clear Chris wants a clear and simple rule; Complicated Karen is concerned with making sure the law produces sensible results in different settings.

Complicated Karen: I've been thinking about how much privacy the law should give to private e-mails held by an ISP. A lot of people think e-mail should be protected by a warrant requirement. What do you think?
Clear Chris: I completely agree. I propose a simple rule: E-mail should be protected by a warrant.
Complicated Karen: Great. Now let's start thinking about some exceptions. Imagine an Internet subscriber wants the ISP to disclose the contents of his e-mail. Maybe he has forgotten the password, or he needs an authenticated version. Should we have an exception for consent?
Clear Chris: Well, yes, of course. If the person really consents, then the government shouldn't need a warrant. That's obvious.
Complicated Karen: Great. What kind of standard would you choose for consent? Knowing? Knowing and voluntary? Intelligent? Is it consent in fact? Would you allow implied consent? And what about third party consent? How about business e-mail?
Clear Chris: Woah, that's a lot of questions! I don't really know, to be honest. I just want the exception to be clear so people can understand it.
Complicated Karen: Sure, I agree, clear is great. At the same time, we need to think about just what kind of consent you have in mind. Otherwise it will just punt the issue for the courts to make up the law later on. Moving along, what about an exception for emergencies? Should we have an emergency exception? For example what if the police tip off the ISP that the e-mail is being used by a kidnapper, and the government would need several hours or more to get a warrant. Should we allow emergency disclosure if the ISP wants to disclose?
Clear Chris: I don't know, once we start getting exceptions, it seems like the exceptions are going to swallow the rule. But I'm not a nut; if there's really a kidnapping, and the ISP is willing to disclose, I think an emergency exception for kidnapping is reasonable. But I want the exception limited to kidnapping.
Complicated Karen: How about terrorists attacks? Serial killers? Maybe we should craft a general exception for severe emergencies?
Clear Chris: I'll have to think about that one; I'm pretty skeptical, but I'm not sure I would want to totally rule that out. Let's come back to that one.
Complicated Karen: Sure. What about if the ISP is outside the U.S.? What then?
Clear Chris: Who has an e-mail account outside the U.S.?
Complicated Karen: A lot of people do, actually. Someone in the US might have an account with servers in Canada. And for that matter, someone in Paris might have a Gmail account in the U.S. Do you want to require a warrant for all of these cases?
Clear Chris: I've never thought about that one, I have to admit. But well, yeah, sure, let's have a warrant requirement for those. I want a clear and simple rule, so let's keep it clear and simple.
Complicated Karen: Sure, that's fine. But to do that, we're going to modify some other laws. Under current U.S. law, U.S. officials can't get a warrant for overseas: warrants are traditionally for U.S. use only. And how do you want to create U.S. jurisdiction over crimes occurring abroad? If a person commits a crime in France, that can't authorize a U.S. warrant under U.S. law. We either need to negotiate a treaty with the French government to handle that, or else we can say that French crimes committed in France are U.S. crimes, too, allowing warrants to be issued in the U.S.
Clear Chris: Yikes, are you nuts? Suddenly you're talking about the treaties and French law, and all I wanted to do was have a simple rule! You keep trying to make things complicated. Why not just make it simple?
Complicated Karen: I'm trying to keep it simple, actually. But to make the law what you want it to be, you need to think about these issues: Otherwise you'll announce a simple rule but it won't have any legal effect because of other aspects of existing law.
Clear Chris: Lawyers! You guys always like to make things complicated; No wonder you bill by the hour.

  Of course, none of this suggests that clear rules are bad. To the contrary, they are the ideal, in my view. But clarity and simplicity are only some of the goals of legislation, and I don't think it works to simply assume that we necessarily want the law to be very simple and very clear no matter what. Put another way, sometimes the law is complicated not because of those darn lawyers, or because of evil interest groups, but because it needs to be complicated to avoid being an ass.