Dexter is a serial killer who only kills serial killers. It's a show about justice.
How about a show called Rapster? A rapist who only rapes rapists.
Or how about Molester?
It's about a priest who travels back in time and molests child molesting priests when they're children.
But then, wouldn't he have to molest himself?
Sometimes, I think the only justice for you would be having to answer your own questions.