Legally speaking, that's backwards AFAIK. If you don't give people a license, they are not allowed to do anything with your code — full copyright protection is

Legally speaking, that's backwards AFAIK. If you don't give people a license, they are not allowed to do anything with your code — full copyright protection is something you have to opt out of, not into. You might say that putting it on the Internet and encouraging people to use it is an implicit license, but you're on thin ice at best if you're depending on that unwritten license. I doubt most legal departments would even consider the suggestion. Even if you really, really trust the author, someone could acquire the rights to the code later on and sue your pants off if you don't actually have a valid license. Would you be able to successfully argue "But this other guy posted it on the Internet, so obviously I'm allowed to use it as I see fit"? IANAL, but I really doubt it.