An affair with Lewinski wherin he uses his office to benefit her for engaging in sexual activities with him is certainly illegal - and the accusation that he did this (and its converse of punishing those who did not comply) as a pattern of behavior was the basis for the lawsuit.
No it's not.
and the accusation that he did this (and its converse of punishing those who did not comply) as a pattern of behavior was the basis for the lawsuit.
No it wasn't. The basis for the Jones lawsuit was that Clinton came on to her. She wanted to use Lewinsky as evidence to establish "pattern" in the civil case. IIRC, Clinton wasn't charged either, although there were penalties.
The general point is a simple one - the law asks for participants to give truthful testimony, or none at all if you are the target of the case. And lying to investigators carries a risk of criminal prosecution.