quote from the article:

"Most simply ride with friends in their free time, but some have been involved in violent incidents while in “biker” mode. An Arizona officer goes to court Thursday for allegedly assaulting a bar patron who made comments about his bike gang's “colors.” According to Katz, it doesn’t help that many of the law enforcement motorcycle clubs model themselves on outlaw gangs like the Hells Angels and the Warlocks. They wear the same kind of patches, ride the same bikes, and, sometimes, break the same laws."

“You can’t act like something and not become it,” said Katz, who spent three decades investigating bike gangs. “You can’t be a biker by night and a cop by day.”"

Lines blur between cops and bikers across the country - Investigations

http://www.dnainfo.com/new-york/20131008/washington-heights/off-duty-cop-expected-be-charged-beating-of-suv-driver-sources-say