The PIT is not applicable in every situation, and many factors affect the usefulness of the technique. Many of these factors relate to safety concerns: typical police regulation recommends that an officer not attempt the PIT at speeds greater than , and requires careful choice of location, considering all possible effects on other traffic vehicles and pedestrians. Because of the police department's potential liability for the injury or death of not only of the occupants of the target vehicle, but also bystanders, most departments limit its use to only the most high-risk scenarios. Most departments specify that the PIT should only be used to stop pursuits that are immediately dangerous and ongoing. When possible, a minimum of three pursuers should be present when a PIT is executed: one as the PIT vehicle and two following at a greater distance to react to the results.