I think the confusion for many is the term "tought crime" itself. The concept means that the "crime" exists only within the mind of the person.
So let's, just for fun, follow through on that. You think a criminal thought.
Now, who (besides yourself) knows that you had the thought? Who is going to report that you had the thought to the appropriate authorities? What would those authorities use as some sort of probable cause to investigate/arrest you? What evidence would be presented to a trial?
Even if someone else was aware of your thought, a judge and/or jury would have to be convinced that the thought had been there and be able to make a judgement that teh thought was in fact, criminal. So the DA would have to present their case at trial and then your lawyer (Perry Mason himself!
) would put you on the stand and ask you "Ms. Boomerang, did you or did you not have the thought you are accused of?" And you, under threat of execution, would say "No!". Perry would the immediately turn to the judge and request a summary dismissal due to the State's lack of evidence which would be granted and you'd walk out of the courtroom a free woman again.
A true "thought crime" can't exist at this point in time because we have no way to capture an actual thought from someone as the fictional Thought Police had in
1984. Even if there were such laws, there is no way to prove that the crime happened. It seems pretty futile to prohibit something that could never be proven.
Whether someone may or may not re-offend in the future isn't determined based on thoughts. The court would have to look at past
acts and attempt to use them as a predictor of possible future offenses.