From Watts v. McKinney, No. 03-16665 (9th Cir. January 10, 2005):
Denial of defendant's claim of qualified immunity is affirmed where "kicking a helpless prisoner's genitals" constitutes cruel and unusual conduct in violation of the Eighth Amendment.
What next, Ninth Circuit? No human pyramids? No electrodes? Why are you tying our nation's hands, or whatever?
If you have forgotten (or never had to learn it), the defense of qualified immunity protects an official if a reasonable person in his or her position would not have known the action was a constitutional violation. It's designed more or less to protect officials from millions of prisoner claims over actions that may well be reasonable under the circumstances.
Ball-kicking does not seem all that close to the line, frankly.
The court said that the defense lawyer's zeal in making this argument was commendable, but "zeal needs to be tempered by common sense":
To suppose that any reasonable person, let alone a trained prison officer, would not know that kicking a helpless prisoner's genitals was cruel and unusual conduct is beyond belief. The Supreme Court did not need to create a catalogue of all the acts by which cruel and sadistic purpose to harm another would be manifest, but if it had, such conduct would be near the top of the list.
On the other hand, maybe that kind of catalogue would be a good idea.