What if you don't want to answer the cops' questions?

More than once I’ve read or heard the advice—including from a lawyer—that it’s better not to answer any questions from the police.

I suppose there must be exceptions, times when you would—such as when you could give someone a solid alibi.

But let’s say it’s not one of those cases and you are not willing to answer the questions. What do you say? And is there any particular law that you’d want to cite?