Recruiting prisoners is actually a huge pain - they're one of several protected categories (along with children and soldiers) based on the potential that their

Recruiting prisoners is actually a huge pain - they're one of several protected categories (along with children and soldiers) based on the potential that their "consent" isn't really all that consenting. In my mind, this exists for good reason, but it does kill almost any study that doesn't absolutely need to be conducted on prisoners for their own benefit.