Do you have a right to wear your hair long in prison if that's an important component of your religious beliefs? That's the question asked to -- and answered by -- this opinion.
Given the composition of the panel (Judges Paez, Pregerson, and Tashima), you can probably intuit the answer they gave. Which is: "Yes". Judge Pregerson's opinion does a good job of arguing for such a result. Particularly compelling, I think, is his introductory, five-paragraph statement of facts. It really does let the reader know what's at stake, and fairly effectively convinces the reader that this is no made-up, bogus claim of religious freedom, but is in fact an important part of the plaintiff's religion. (Judge Pregerson doesn't mention it, but even the plaintiff's name -- "Warsoldier" -- articulates some reason to believe that the plaintiff is indeed really into his Native American religious background).
Of course, a claim of religious freedom can fairly be outweighed by compelling penological interests and the regulation is the least restrictive means of advancing these interests. And, fear not, California articulates a wide and varied set of interests that are allegedly advanced by the restriction on long hair (e.g., "You could hide a weapon in there!").
But Judge Pregerson yet again does an impressive job of convincing the reader that these alleged claims are either frivolous, overblown, or not advanced by the least restrictive alternative. For example, he notes that many non-California prisons grant religious exemptions and allow long-haired inmates without any evidence that any untoward effects have resulted therefrom. Moreover, the fact that California allows female inmates to have long hair also, in my mind, goes quite a long way towards establishing that the alleged interests that are ostensibly advanced by the "no hippie hair" regulation are either nonexistent or uncompelling.
So, in the end, Judge Pregerson holds that, if your religious beliefs require it, you can have long, flowing, Fabio-like hair. Little solace to old, balding people like me, admittedly, who probably couldn't grow long hair (at least without looking somewhat absurd) if they tried. But important for people like Billy Warsoldier.