When a police officer is caught flagrantly misbehaving on video, the most that superiors and union officials typically concede is that he's an exception to the rule, a "bad apple." That can be true. There are something like one million cops in the U.S. Many do their jobs ethically, and even the best run police agencies sometimes find themselves employing a cop whose behavior is anomalously awful.

But the modern era of videotaped police brutality, which began when a group of LAPD officers nearly killed Rodney King, has also revealed a darker variation: the occasions when multiple cops participate together in obviously extra-legal assaults, where many throw punches and kicks and still others are silent bystanders whose complicity typically grows when they accede to fabricated police reports.

The latest illustration of this pattern occurred last week in San Bernardino County, California, where an NBC news helicopter captured the end of an unusual chase: a suspect fled on horseback across the wilderness while cops gave chase. In an initial use of force, one deputy used a Taser to knock him from his mount. "He then appeared to be stunned with a Taser by a sheriff's deputy and fall to the ground with his arms outstretched," NBC reports. "Two deputies immediately descended on him and appeared to punch him in the head and knee him in the groin."