Convicted Felon Using Visa Waiver to Enter Europe?

[JoelWhy]

I am trying to determine whether a U.S. citizen convicted of a felony in the U.S. is able to use visa waiver to enter Europe (Spain and France, in particular.) I assumed that they would be prohibited from using VW, but everyone I have spoken with at the consulates (I even spoke to a member of the federal police in Spain) says it's ok, and that they don't check criminal records when using VW, so it doesn't matter.

I understand that you can almost certainly get in w/o a problem, but I really need to know whether it is LEGAL (as opposed to merely practical.) Can anyone tell me for certain (preferably with some kind of citation!)