在美国，警察遇到危险，不是一定要冒险的：

“The Supreme Court has made it clear,” said Patrick, who wouldn’t comment specifically on the Farmington case. “A police officer can let the public take the risk, take [the risk] upon himself or put it on the individual who brings the danger in the first place. That’s what law enforcement is for — to protect the community. They have to protect themselves [first] to do that.”

http://bangordailynews.com/2011/11/25/news/state/police-officers-must-protect-themselves-first-former-fbi-instructor-says/