Cortez v. Skol (9th Cir. - Jan. 26, 2015)

Judge Friedland seems right here.  When prison policy says not to walk three hostile, half-chained, high-security inmates by yourself through "no man's land" where there are no cameras and no backup, a jury might find that it's indeed unreasonable to do so.  Which means that when you nonetheless elect to do so because you're "busy", and two of the prisoners brutally attack and stomp on the head of the handcuffed third until he suffers serious brain injuries, that same jury might perhaps find you liable.