Does anyone know anything about mock jury trials?

Are they scams, are they really worth it to make some extra money? My s/o got a phone call, inviting him to do one of these things (he agreed to do it) but I’m just worried they might try and coerce him into signing up for crap completely unrelated to the mock trial. This isn’t an online thing, it’s in a physical location.
He’s going to get paid a little over a hundred dollars, so at least he’s making some money but I’m still wary.