> But not all laws should expire. Having, say, the crime of murder expire would be quite unhelpful.

I'm pretty sure that laws like that one would be renewed before expiration anyway -- and the current context would allow re-evaluation of penalty as well, which might be something useful to reconsider every couple of decades.

But that renewal provides a hook for legislators to attach all kinds of distasteful things to it.

It would be an excuse for political and legislative brinkmanship on a schedule. They can always make changes to the details without a clock adding artificial urgency. It's clear it's the kind of law we want on the books, and to have a penalty on the books, indefinitely. Unlike, say, the chicken tax.

One question then, is whether laws are generally more like murder, or more like the chicken tax. I don't know, but I suspect there are more chicken-tax-like laws by a considerable margin.