I don't know if it's harder but when you're playing a real person you want to honor their memory - even if they're a criminal or someone that the public loathed. That can be challenging.
The question arises whether all lawyers are the same. This is like asking whether everything that gets into a sewer is garbage.
Westerns was why I got into the business. I grew up on a small farm in California and all I ever wanted to do was to play gangsters and cowboys in movies.