Are CC licenses and others enforceable in a court of law?
Yes, Creative Commons licenses are drafted to be enforceable around the world, and have been enforced in court in lots of jurisdictions all around the world. To CC’s knowledge, the licenses have never been held unenforceable or invalid.
CC licenses contain a “severability” clause. This allows a court to eliminate any provision determined to be unenforceable, and enforce the remaining provisions of the license.
If you are planning on using CC work make sure you learn how to properly give attribution.
What happens if someone applies a Creative Commons license to CC work without knowledge or authorization?
CC alerts prospective licensors they need to have all necessary rights before applying a CC license to a work. If that is not the case and someone has marked your work with a CC license without your authorization, you should contact that person and tell them to remove the license from your work. You may also wish to contact a lawyer. Creative Commons is not a law firm and cannot represent you or give you legal advice, but there are lawyers who have identified themselves as interested in representing people in CC-related matters.