There are, as near as I recall, certain other specific lies that are in the State's jurisdiction, such as giving the police a fake name. Something like 15 years ago, SCOTUS also ruled against a guy who refused to give the police his name when he was questioned.
For the most part, you can tell a regular cop all sorts of lies, with some exceptions like your name. Lying to the FBI is against the law, if you're being questioned in regards to a criminal matter - I am unsure about civil matters. You sure as hell can't lie on the forms you sign when you cross the border. No, they will be right pissed if you do that.
I am not a lawyer, but I have spent some time in court, dated a lawyer, and taken a few electives on the subject. So, this isn't legal advice but I'm pretty sure this is reasonably accurate.
Sort of off topic, they pick students to hold mock trials, hearings, etc., and do this in a mock courtroom at many universities. If you audit the right course, you can volunteer and you can learn all sorts of neat things. You can also just go sit in the courtroom at your local court. It's open to the public, most of the time. It's a great way to learn more about procedure.
Anyhow, like always, consult a qualified legal professional in your jurisdiction, should you need legal advice.
If digital currencies really take off (i.e. beyond just a niche group of speculators and early adopters), expect customs forms to include a question on it, then.
You already have to promise not to be a member of Al Qaeda on some immigration forms.