Pelican Bay is a supermax prison, and the SHU is for the "worst of the worst". It's unlikely they put first timers there. As for the rationale: since the law p

Pelican Bay is a supermax prison, and the SHU is for the "worst of the worst". It's unlikely they put first timers there. As for the rationale: since the law prohibits you from actively torturing/executing prisoners, you have to resort to more creative means of inducing suffering (and thus hopefully compliance). Removing and limiting all privileges, personal belongings, and mental stimulation (including a view other than drab gray concrete walls, or sunlight) is a guaranteed way to get people's mental state to deteriorate. The worsening of the psychological makeup is thus by intent. This is meant for people who are deemed unredeemable, as well as a punishment to threaten prisoners in less severe prisons with: "We have an even worse place for you, should you cause too much trouble." It's torture, of course, except it's legal.