I found some code on the web. The web page doesn't make any mention of a license, and the download doesn't make any mention of a license. What are the license implications of using that code in the US? Is there such a thing as an implicit license?
If the code doesn't have a license, it is still copyright by it's author, which means you cannot use nor publish it without their express permission [assuming you're in the U.S. and the code is from a country we're treaty obligated to enforce copyright protections for].
IANAL, but I think it depends on local copyright laws. I have a feeling that if it gets taken to court, the winner will largely depend on the deepness of your respective wallets.
There's no such thing as an implicit license. A code is implicitly copyrighted the moment it is written, and, by default, you have no legal right to redistribute it, or produce derived works from it (of course, the author might not mind, but that's another matter entirely). In other words, lack of license is roughly the same as "look but don't touch" license.