The video of Minneapolis police officers apprehending George Floyd is horrifying: One planted his knee on Floyd’s neck and apparently suffocated him. The video, like any other source of information, does not tell the whole story. But the fact remains that police actions probably led to Floyd’s death in their custody.

The incident reignites questions about the use of force by police. Officers are trained to manage confrontations professionally and to safeguard the wellbeing of community members, even people they arrest. These lessons should be taught in the academy, then regularly reiterated in ongoing professional training. The officers who arrested Floyd ignored this training, to tragic effect. One of the disturbing things about the video is that it showcases a veritable checklist of specific things officers are taught not to do.

First, the “prone” position Floyd was placed in — face down with his hands behind his back — is intended to be a temporary position to put someone in handcuffs and possibly search for weapons. Being in that position puts weight on the subject’s chest and abdomen, which makes it harder to breathe. For more than 20 years, police have known that “positional” or “compression” asphyxia can occur when someone cannot draw sufficient breath, even if they can breathe enough to gasp or speak. Time in the prone position needs to be kept to a minimum because of the risk of positional asphyxia — which is elevated when the subject is obese, frail or being held down by officers, or has had their breathing compromised by, for example, alcohol, drugs or exposure to pepper spray.

As soon as practical, officers should move the person into a “recovery position” by rolling them onto their side, sitting them up or having them stand. And officers should absolutely do so if the person exhibits signs of medical distress. But Floyd was kept prone with pressure on his neck while handcuffed for almost eight minutes, including almost four minutes after he lost consciousness.

Second, officers might need to hold someone down in the prone position, but they should do so by putting their shin across the subject’s upper back, not the neck. Pressing on someone’s neck risks damaging the cervical spine or breaking the hyoid bone, which can be fatal. In this case, one officer — identified by local media outlets as Derek Chauvin — kept his shin across Floyd’s neck the entire time.

Third, officers have an obligation to monitor the health and wellbeing of anyone they have in custody, especially after an arrestee is properly secured. According to a Minneapolis Fire Department report, medics were initially informed “only that [Floyd] had trauma to his mouth.” They discovered that Floyd was unconscious and had no pulse when they arrived on the scene. This is information that officers should have had and shared with responding medics.

Fourth, one officer — identified by local media outlets as Tou Thao — stood there and interacted with bystanders without ever attempting to ensure Floyd’s wellbeing or put him in a safer position. The failure to intervene is a deep-rooted cultural problem in policing, but it was simply unconscionable in this case. Many modern police agencies, including the Minneapolis Police Department, have adopted “peer intervention” policies that require officers to step in when they see a colleague doing something they shouldn’t. Some have gone further, like the New Orleans Police Department, which has put its EPIC (Ethical Policing Is Courageous) program at the center of agency culture.

Worse, Thao made no attempt to constructively engage with the bystanders, described in the fire department report as “upset but not unruly,” or to just stand silently. Instead, he made comments such as, “This is why you don’t do drugs, kids.” This suggests not only a lack of respect for Floyd’s privacy and health, but also a lack of concern about provoking bystanders in an already contentious situation. Police training emphasizes professionalism, and Thao’s failure to exercise good judgment is almost as concerning as his blatant disrespect.

Floyd’s death was a foreseeable consequence of the officers’ actions. They knew they were being observed and recorded, but continued to engage in obvious misconduct. The litany of problems in this case suggests that the officers were either shockingly incompetent or disturbingly indifferent to proper police procedure.

We’re still learning more about the case, but the episode suggests poor training, insufficient supervision, a dangerously adversarial mind-set, a culture of entitled authoritarianism and a disregard for the lives and good opinions of people of color. Those are all values at odds with good police work — values that rigorous training programs and quality supervision seek to stamp out.

Floyd’s death is likely to reinforce the perception that police officers are not members of the community but are rather an adversarial, occupying force. To earn and keep the trust of the citizens they serve, officers need to follow their own policies and procedures.

Twitter: @PoliceLawProf