Why don't the police fire warning shots? That's a question that comes up a lot, especially after controversial shooting deaths.Last fall, the International Association of Chiefs of Police and 10 other law enforcement groups got together to work out a consensus policy on the use of force — a sort of model document for local departments that want to update their rules. When the document came out in January, it contained a surprise: It allowed for warning shots.For police trainers and use of force experts around the country, that news is still sinking in."The idea of warning shots has been prohibited for decades in policing," says Lou Hayes Jr., a police officer and trainer with the Virtus Group Inc. "And to now open the door up again is pretty eye-opening."There's never been a binding national rule against warning shots, but the IACP used to recommend that departments ban the practice. Leading agencies such as the New York Police Department have long had such bans in place.The main concern is the risk. "When you raise the gun and blindly fire, you don't know where that bullet will land," says Massad Ayoob, a longtime cop and widely respected firearms trainer. "A few decades ago I followed a case in New England where the guy raised his gun, fired what he thought was into the air, and the bullet struck and killed someone on the top floor porch of a nearby tenement building."Firing at the ground can be just as dangerous, especially on streets or confined spaces. And Ayoob says the payoff usually isn't what people imagine."Movies show people firing a shot in the air and the running man stops," Ayoob says. "And that just ain't how it happens in real life." Often, he says, the gunshots just persuade a suspect to run faster.Return of an old toolAyoob says fear of mishaps drove warning shots out of policing by the time he started as a cop in the 1970s. But now it may be making a comeback."There was a lot of discussion," says the IACP's Terry Cunningham, describing the process that led the 11 law enforcement organizations to include warning shots in the new consensus use of force policy. Cunningham was struck by the anecdotes of situations in which warning shots saved a life — or might have, had they been allowed.The new policy still sets strict conditions for warning shots:1. The use of deadly force is justified;2. The warning shot will not pose a substantial risk of injury or death to the officer or others; and3. The officer reasonably believes that the warning shot will reduce the possibility that deadly force will have to be used.But Cunningham says the motivation for the change is to give officers a little more wiggle room when faced with a threat."We're kind of entering into this new environment in use of force where everybody is trying to learn how to better de-escalate," Cunningham says.Many police trainers have come to believe that overly rigid use of force rules, however well-meant, may sometimes leave officers with no other option than to kill someone. The new model policy is a response to those concerns."Why not give the officers more tools?" Cunningham says. "I think it's the right thing to do."It's still up to local departments and trainers to decide whether to follow the national groups' lead on warning shots. So far, reactions have varied. In an email to NPR, the NYPD says its policy banning warning shots "will not be amended."But trainers and experts are more positive. Greg Meyer, a retired Los Angeles Police Department captain and use of force expert, calls the new policy an "overdue good idea."Shooting to woundDave Blake, a retired police officer who trains officers for high-pressure situations, says he is on the fence. He points to some research suggesting warning shots can persuade suspects to give up, but he thinks more study is needed."I don't think police officers are lab rats," he says. "And I think we need to be very careful with — because of political pressure or social issues — how far we go in mass implementation of new programs and policies."Police trainer Hayes welcomes the new flexibility, but he says there will be pushback, especially from officers who worry about creating an expectation among the public that warning shots should precede every use of deadly force.He says allowing warning shots also raises another, more controversial question: whether cops should try to shoot to wound.Police usually scoff at the suggestion that they try to shoot someone in the leg before aiming at the suspect's center of mass. They call it "Hollywood thinking" because it assumes sharpshooting skills that are simply unrealistic, especially in a chaotic situation.But in a recent blog post, Hayes said that the blanket prohibition against "shooting to wound" might have to be reconsidered once you've allowed for warning shots."A warning shot is essentially deadly force," Hayes says. "It's just purposely aimed away from a person. So if we're going to aim away from a person, why is there not some incentive to potentially aim for a nonvital area on a person?" Allowing warning shots, he says, may open the door to the idea of a "spectrum of deadly force."That's not a logic most trainers accept, but firearms trainer Ayoob does worry that allowing warning shots "opens a can of worms." The rules allowing police to use deadly force are clear: If an officer reasonably perceives someone to be an imminent mortal threat, the officer is allowed to shoot. Adding the possibility of warning shots to that decision-making process could confuse things."If a danger ipso facto is that immediate, why are we taking our eyes off the threat and firing a warning shot?" he asks. "If deadly force is justified, deadly force should probably be applied." Copyright 2017 NPR. To see more, visit http://www.npr.org/.