Lying to federal investigators is usually a crime of some sort. Whether lying can really be Constitutionally prohibited (and if so, when, and what the rationale

Lying to federal investigators is usually a crime of some sort. Whether lying can really be Constitutionally prohibited (and if so, when, and what the rationale is) is an interestingly thorny area of first-amendment law. Some laws against lying are very old; for example, libel is a special case of lying. And in the commercial sphere, laws against false advertising have been upheld. But the dividing line is not that clear. Eugene Volokh had a series of posts on the subject, spurred by a U.S. law (later overturned) that made it illegal to lie about having received a military decoration: http://www.volokh.com/category/freespeech/knowingly-false-statements-of-fact/ http://www.volokh.com/category/freespeech/knowingly-false-st...