NEW YORK—Saying the initial projectiles often irreversibly shift the dynamic between driver and officer, a study published Tuesday in the Proceedings of the National Academy of Sciences found that the first bullets fired by the police during a traffic stop consistently dictate how the rest of the interaction will go. “Often within the first 45 gunshots, we know whether the stop will end positively or negatively for the driver,” reads the study in part, which examined police body camera footage of thousands of routine vehicle stops to determine that the manner in which the earliest bullets were fired reliably predicted whether the driver would be merely injured or killed. “We also found that Black men are far more likely to perceive being shot in the face at the beginning of the stop as an aggressive act. This suggests that all that it takes is a few misplaced bullets to dramatically escalate the situation past a point of no return.” In response to the study’s findings, dozens of police departments reportedly pledged to train their officers in how to end such traffic stops with a single well-placed bullet.