I occasionally support government legislation as a means of doing things that just can't be done with current technology. Copyright is a case in point. Using nothing but contracts, you could easily say: "Nobody has access to this information unless they promise not to give it to anyone else." Which gives you the same effect as current copyright law. If anyone is responsible for leaking information, at any point in their whole life, nobody ever shares anything with them again and they may be liable for an arbitrarily large amount of legal damages. Furthermore, by using my copyrighted material, you agree not to use anyone else's copyrighted material that may have been published by someone else.
This condition - requiring more computing power and better tracking than we now have - can be duplicated by creating copyright legislation that people can "opt out" of. In other words, Lee Daniel Crocker can decide to ignore copyrights (and lose the ability to copyright his own work), but then his favorite comics pages might refuse to let him in, and some employers wouldn't hire him.
Our modern haphazard copyright enforcement is actually better, because
without the patina of voluntary compliance, it's morally easier to
advocate changes to the system and ignore the unjust parts.
--
sentience@pobox.com Eliezer S. Yudkowsky
http://pobox.com/~sentience/AI_design.temp.html
http://pobox.com/~sentience/singul_arity.html
Disclaimer: Unless otherwise specified, I'm not telling you
everything I think I know.