In general, teaching which is not intended to facilitate crime is protected speech. (Beating a polygraph isn't inherently, a crime. It depends on the context.) But, if you know or reasonably should know that you're aiding in the commission of crime, then you have committed a crime. You needn't be explicitly informed of criminal intentions by your students. Willful ignorance will not protect you from prosecution.
So, for example, mere publication of a book on polygraph countermeasures is probably protected speech, particularly if the information is presented as valuable data for public debate, rather than instructions for would-be criminals. (Don't take my word for it, and remember I said "probably.") But, if a person coaches individuals, and a reasonable person in the same position would suspect criminal intentions, then the coach is probably no longer engaging in protected speech.
One wonders, then, where the line is drawn. How much does one have to know about his students before it becomes actual knowledge of willful ignorance, both of which can result in conviction? One can reasonably assume that at least some percentage of all polygraph evaders do so in a context where it's criminal. How does this affect the legality of teaching countermeasures in a one-on-one context?
It turns out that the distinctions are subtle, and the case law complex. I would recommend the following read if you're interested in the finer points:
The above article doesn't provide a clear answer about teaching polygraph countermeasures, specifically. If anything, it shows that the outcome will depend on a lot of particulars of the case. I don't think one can answer the question in a general sense.
So, for example, mere publication of a book on polygraph countermeasures is probably protected speech, particularly if the information is presented as valuable data for public debate, rather than instructions for would-be criminals. (Don't take my word for it, and remember I said "probably.") But, if a person coaches individuals, and a reasonable person in the same position would suspect criminal intentions, then the coach is probably no longer engaging in protected speech.
One wonders, then, where the line is drawn. How much does one have to know about his students before it becomes actual knowledge of willful ignorance, both of which can result in conviction? One can reasonably assume that at least some percentage of all polygraph evaders do so in a context where it's criminal. How does this affect the legality of teaching countermeasures in a one-on-one context?
It turns out that the distinctions are subtle, and the case law complex. I would recommend the following read if you're interested in the finer points:
http://www2.law.ucla.edu/volokh/facilitating.pdf
The above article doesn't provide a clear answer about teaching polygraph countermeasures, specifically. If anything, it shows that the outcome will depend on a lot of particulars of the case. I don't think one can answer the question in a general sense.