For some reason you're getting downvoted, but clearly people have some misconceptions about libertarianism, perhaps confusing it with anarcho-capitalism.
I'd agree that contract enforcement (including to combat fraud) along with the non-aggression principle, are the primary defining principles of libertarianism, regardless of the particular school or wing of libertarianism in discussion.
Libertarians are absolutely in favor of using court systems to sue people for fraud.
The belief in contract enforcement, and stopping fraud is a defining feature of libertarians.