How would we check if "Mathematicians are generally more Law Abiding?"

In Local Validity, Eliezer notes:

But I would venture a guess and hypothesis that you are better off buying a used car from a random mathematician than a random non-mathematician, even after controlling for IQ. The reasoning being that mathematicians are people whose sense of Law was strong enough to be appropriated for proofs, and that this will correlate, if imperfectly, with mathematicians abiding by what they see as The Law in other places as well. I could be wrong, and would be interested in seeing the results of any study like this if it were ever done. (But no studies on self-reports of criminal behavior, please. Unless there’s some reason to believe that the self-report metric isn’t measuring “honesty times criminality” rather than “criminality”.)

I’m guessing such a study hasn’t been done, but it seems like the sort of thing you should be able to actually go and check.

I’m interested in both:

What is the expensive, impractical study you could hypothetically run that would give strong evidence about this question?
What’s the cheapest, practical study we could run that would provide at least some meaningful data about it?

[Question] How would we check if “Mathematicians are generally more Law Abiding?”