Carl Bryan had a shitty morning.
Now, we all have bad days, days that would look highly unfortunate if described painstakingly in print (for instance, in the factual section of an opinion by the Ninth Circuit Court of Appeals).
But Carl's morning was unusually bad. Carl Bryan's morning involved a crescendo of arrested-adolescent personal dysfunction ("He began crying and moping, ultimately removing his t-shirt to wipe his face") that ended unpleasantly when Officer MacPherson of the Coronado, California Police Department tased him, causing him to fall face-first onto the unforgiving asphalt, breaking his teeth and suffering facial contusions.
The question presented to the Ninth Circuit was this: did Officer MacPherson violate Mr. Bryan's rights by tasing him for the offense of standing outside his car in his tennis shoes and boxer shorts, "yelling gibberish and hitting his thighs"?
It's worth reading the whole opinion, but to cut to the chase for you the answer is yes with a but. Yes, it was excessive force to tase Mr. Bryan when he was really doing nothing but standing there being highly dysfunctional. But police officers like Officer MacPherson could reasonably be confused about whether it was appropriate to tase someone for standing there in his underwear sniveling. Because law is complicated and stuff, and who can keep track of all the people you should or shouldn't tase? Quite frankly I'm not certain that the Ninth Circuit can keep it straight. So Officer MacPherson is immune from suit.
In the meantime, Carl Bryan has learned that if you stand there in your underwear acting like a dork, some law enforcement officers may be sufficiently intimidated to use non-lethal force on you.