The International Association of Chiefs of Police issued guidelines for coping with suicide bombers in 2005, including a recommendation that officers need not wait until the threat is imminent before using deadly force.
Within weeks of that report, London police officers using a similar policy shot and killed a man they had wrestled to the floor of a train because they incorrectly suspected he had a bomb.
Anti-terrorism policies often allow officers to fire without warning a suspect to surrender because a warning might simply alert the bomber to detonate.
Sheri H. Mecklenburg, an assistant U.S. attorney, wrote in the magazine of the international police chiefs group in 2007 that Americans are accustomed to debates about whether a suspect made an overt threat to harm someone.
"In the context of suicide bombers, however, this debate is irrelevant. Suicide bombers always pose an imminent threat of death and serious injury, whether they are moving toward or fleeing from their target, for at any time they may detonate," Mecklenburg wrote.