This much seems clear: Last Sunday, Hope Coleman called 911 seeking help for her mentally ill son, Terrence. What happened after emergency medical technicians and police officers arrived at the family’s apartment is less clear.

Two emergency medical technicians and two police officers responded to the call. The EMTs entered the apartment while the officers investigated an unrelated disturbance up the street. According to the chief of Boston Emergency Medical Services, Terrence Coleman initially cooperated with the EMTs before the encounter turned violent in the hallway outside the apartment when Coleman retrieved a steak knife from his bag. A struggle ensued and one of the EMTs radioed for police assistance. The police rushed to the scene, providing the EMTs with an opportunity to escape; apparently Hope Coleman left around this time as well. The EMTs allegedly heard the officers yell out, “Drop the knife,” before two shots rang out, killing Terrence Coleman. Hope Coleman disputes this account and insists her son did not pose a threat. The key legal issue in this incident, of course, is whether the shooting was justified based on a self-defense theory.

In general, a person may use deadly force when threatened with deadly force from another person. The touchstone of this analysis is reasonableness: Did the officers reasonably believe that lethal force was about to be used against them? That is, were they facing an equivalent, imminent threat of harm? This analysis triggers a slew of subsidiary questions: What exactly was Terrence Coleman doing immediately before the officers opened fire? Did he have a knife in his hands? If so, how was he holding it—in a raised fashion, down by the side, and/or pointed at the officers? What was the distance between him and the officers? What, if anything, did the officers know about Coleman’s history?

There are lots of potential witnesses in this case who can offer testimony about the events leading up to and occurring after the killing. These include the EMTs’ recollection of the encounter prior to the arrival of the police; Hope Coleman’s assertion that her son was unarmed before her departure; law enforcement officials’ accounts of past interactions with Terrence Coleman that involved knives or at least the threat of them; and evidence from crime scene investigators about the retrieval of a knife in the hallway. But it appears as if the only witnesses capable of providing direct evidence about what transpired at the precise moment of the shooting are the two police officers whose objectivity is inevitably called into question by the circumstances.

It didn’t have to be like this. The police union long thwarted efforts to launch a body camera pilot program in Boston before Commissioner William Evans succeeded in making modest headway and, even then, only after a Suffolk County judge denied a filing by the union to halt implementation in September.  At present, 100 police personnel are using the devices as part of the pilot; the Boston Police Department has stated that the two officers involved in the Coleman shooting were not wearing cameras. What if those officers had cameras on their lapels that recorded what they were facing during the incident?  Would the community, and most importantly Hope Coleman, have more clarity about what happened? Would the recording have shed light on any possible self-defense argument?

Body cameras are not a panacea to the criminal justice system’s many ills. And they do not come without risks or burdens. They can malfunction; they cost money; they depict an incident only from one vantage point; and they generate a host of administrative and legal issues about storage and public access.  Still, aren’t the downsides of body cameras outweighed by the upsides? How can we quantify the benefit of greater clarity in police-involved shootings?  Regardless of whether any particular recording supports or undermines a police officer’s account, its mere existence might give community members more faith in the process and in those entrusted with the power and the responsibility to protect them.  

The death of Terrence Coleman is a tragedy. One lesson, among many, is that the Boston Police Department should be applauded for pursuing a body camera pilot program and the experiment should be expanded as soon as possible.