If I were wanting to use the justice system to take out a political rival, one of the first things I’d do is use sympathetic legacy media to convince their consumers that the political rival was a criminal and thus deserved the treatment.
I’d simultaneously have sympathetic agencies go through my opponent’s finances, businesses, etc, looking for any kind of criminal activity.
If the agencies couldn’t find enough to put my wealthy rival in jail, I would have my sympathetic agencies use whatever dirt we’d dug up to go after him in sympathetic civil courts and break him financially.
I wouldn’t have to worry too much about the appearance that I am weaponizing the justice system because the media has already convinced a big chunk of the population that he’s a criminal, even though he actually isn’t at this point. On the contrary, those same people would be cheering me on for weaponizing the justice system.