This issue comes up regularly enough that I'm putting this primer here for reference. It discusses some of the critical differences between scientific parlance and common usage, as well as differences between theory, law, and hypothesis. It also addresses common issues about the burden of proof.http://scienceblogs.com/startswithabang ... -of-proof/
Perhaps no word in the English language generates as much misunderstanding as the word theory. In scientific circles, this word has a very specific meaning that’s different from everyday use, and — as a theoretical astrophysicist myself — I feel it’s my duty to help explain exactly what we mean when we use it.
I'm also adding this image from within the article here, mostly because it's well done and cool.