One by one, Minneapolis police leadership and veterans took the stand in former officer Derek Chauvin’s murder trial to view the video footage of him pushing his knee into George Floyd’s neck.

“Pulling him down to the ground, face down and putting your knee on the neck for that amount of time is just uncalled for,” the department’s longest-serving officer testified.

“That’s not what we train,” said an inspector who used to lead the department’s training.

“Not part of our training and is certainly not part of our ethics or values,” the Minneapolis police chief said.

The testimonies offered by these and other high-ranking police officials, punctuated by a chief appearing in uniform, marked an unprecedented courtroom condemnation of an officer by so many of his own department’s leadership, according to law enforcement veterans and legal experts.

They also underscored how policing remains at the heart of a crucial debate that could decide the trial’s outcome. Prosecutors say Chauvin “betrayed this badge,” describing his actions as beyond the pale for police, while the defense argues the ex-officer was using necessary force and “did exactly what he had been trained to do.”

These arguments playing out on a nationwide stage in the closely watched trial mark a watershed moment in American policing, experts and observers say. It is not just Chauvin’s actions in the spotlight but also officers’ willingness to break the so-called “blue wall of silence,” and the justice system’s ability to police its own.

“Policing in America is on trial here,” said Joseph Giacalone, a retired detective sergeant with the New York City Police Department who teaches at John Jay College of Criminal Justice. “Derek Chauvin has done more damage to policing in America than any issue since I’ve been alive.”

During their testimony in the downtown Minneapolis courtroom where Chauvin is on trial, police officials sought to sever his actions from the department that employed him for nearly two decades. The trial continues Monday, with the defense expected to get the case later this week.

In testimony on April 5, Minneapolis Police Chief Medaria Arradondo did not agree that Derek Chauvin used reasonable force in restraining George Floyd. (The Washington Post)

Minneapolis Police Chief Medaria Arradondo fired Chauvin and the three other officers at the scene after video footage showed Floyd, a Black man, gasping for air under the White officer’s knee, setting off a global outcry. Chauvin was charged with murder and manslaughter, while the other three officers were charged with aiding and abetting murder.

When he took the stand in Courtroom 1856 to testify last week, Arradondo offered a bluntly critical assessment of Chauvin’s actions.

Once Floyd “had stopped resisting, and certainly once he was in distress and trying to verbalize that, that should have stopped,” Arradondo said.

Arradondo was followed on the stand by Inspector Katie Blackwell, who once oversaw the department’s training program and now commands the city’s 5th Precinct. Blackwell testified that she met Chauvin two decades ago and later hired him to be a field training officer overseeing rookie officers.

Blackwell, shown an image of Chauvin kneeling on Floyd’s neck, testified: “I don’t know what kind of improvised position that is.”

That they and other officials disapproved of what they saw was unsurprising, said Roger A. Fairfax Jr., a former federal prosecutor and a law professor at George Washington University.

“These top police officials are not defending Chauvin’s actions seen in the video footage because Chauvin’s actions are indefensible,” Fairfax said.

In court, Eric Nelson, Chauvin’s defense attorney, pushed back against the officers’ testimonies, pointing out that one officer had not seen all of the evidence and that others were long removed from patrol work on the city’s streets. He also offered a defense that has been used in other policing cases, saying officers are “allowed to use whatever force is reasonable and necessary.”

During his cross-examination of Sgt. Ker Yang, who runs the department’s crisis intervention training program, Nelson said police uses of force can look unpleasant but “still may be lawful even if they look bad, right?” Yang responded yes.

These debates cut to a central point in the case, a rare courtroom trial of a police officer charged with murder. Prosecutors have long struggled to convict police officers, particularly in deadly shootings and on serious counts. Prosecutors, defense attorneys and legal experts attribute that to a combination of the trust jurors and judges have in police; the legal latitude officers have to use force; and their ability to argue they were only following their training.

But, experts said, these defenses are harder to maintain when other officers, particularly department leadership, take the stand to testify against them.

“The police chief testifying, that’s a game changer,” Kobie Flowers, a former federal civil rights prosecutor and federal public defender who now works in private practice, said in an email. “I’m unaware of any excessive force case in a major American city in which the sitting police chief testified — in full-dress uniform — against one of his own officers.

“You think the jury, after hearing Minneapolis Police Chief Medaria Arradondo testify, is going to vote against him?” Flowers said. “I doubt it.”

More often, he said, police close ranks.

“The police chief is on the side of the accused officer,” he said. “The police chief usually doesn’t testify, but he’s in the gallery of the courtroom with his officers in full-dress uniform sending a clear message to the jury that the police department supports the accused officer. That’s a very visual example of the Blue Wall — a very real reason why juries hesitate to convict officers.”

The parade of Minneapolis police testimony in Chauvin’s trial is likely due to the specific nature of the case, said Michelle Phelps, an associate professor of sociology at the University of Minnesota who has studied community views on the city’s police.

“This case was so uniquely damaging to the department’s reputation … they feel uniquely compelled to correct the record and stand up for the department in this public-facing testimony, in a way that wouldn’t be true if it hadn’t been such an incredibly pivotal and unique case,” Phelps said.

But she does not expect it to set a precedent, because the Chauvin case is so singular. “I don’t expect the chief to now be called in every later prosecution of an officer,” Phelps said.

The trial is, however, meant to send a message on behalf of the Minneapolis police force and officers around the country, said David Carter, a criminal justice professor at Michigan State University and a former police officer in Kansas City, Mo.

“The department wants to demonstrate to the community and the nation that this is not what we’re about,” Carter said. Police around the country, he said, “are looking at this trial to say, ‘This isn’t us, and there needs to be a conviction.’ ”

In other cases where police are charged, Carter said, a senior official might testify about a department’s use-of-force policies. In Chauvin’s case, top police officials are lending their voices to help secure a conviction, which they and prosecutors know is hard to win against officers.

“They all recognize the stakes of this trial,” Carter said.

The degree of police cooperation in Chauvin’s case even breaks with a recent example in Minneapolis history.

In 2018, a Minneapolis police officer was charged with murder for shooting and killing a woman as she approached his squad car after making a 911 call about a possible sexual assault behind her home. In that case, prosecutors said numerous officers refused to cooperate and had to be subpoenaed. Arradondo testified in that case as well, discussing the department’s body camera procedures.

The officer was convicted — a first for an on-duty fatal shooting by a Minneapolis officer — and is serving a 12 ½-year sentence for third-degree murder and manslaughter.

A spokeswoman for the city of Minneapolis declined to comment for this story, saying they were following guidance from the judge in Chauvin’s case and “will not comment on any aspect of the trial proceedings.”

Some in the Minneapolis Police Department say the entire force is on trial along with Chauvin, according to a former senior department official who has spoken with people there.

“It’s really just heart-wrenching to watch a fellow officer do what Chauvin did,” said the former official, who spoke on the condition of anonymity to discuss the ongoing case.

“One of the things that’s been good during the trial, and the chief said this, [the case] is not representative of what the men and women of the Minneapolis Police Department do every day,” the official said. “That’s very important to say. He is not who we are. And all can’t be condemned because of it.”

This parade of testimony has also renewed focus on what is often called the blue wall of silence, which policing veterans and experts define as an unwillingness among officers to speak out against misconduct by their peers.

It’s a pervasive issue in policing, said Flowers, who has prosecuted, defended and sued police officers across his career.

Experts and former police officials said that the code exists but that increasing efforts to diversify police departments, improved training and greatly heightened public scrutiny could already be chipping away at the wall. In some cases, they said, officers might want to avoid being entangled with officers they think are bad news or could create trouble for them, including possible legal danger.

“Faced with going to prison yourself, there’s no blue wall of silence, I’m sorry,” said Giacalone, the former New York police official. “That makes people talk. There’s no such thing as the blue wall of silence at that point when you’re facing 25 years to life.

“People … including cops, will act in self-preservation faced with extreme amounts of jail time,” he said.

Cases like Chauvin’s could also have a deterrent effect, some experts said. If he is convicted and the other officers charged in the case are as well, it could send a warning to other officers who have jobs and families and fear losing them.

The Chauvin trial also is an unusually prominent case with extensive video footage and witness accounts.

“When you’re not there, it is always easy to say, ‘I don’t know what the circumstances were, I don’t know what the pressure from the crowd was, I don’t know what all of the factors were that you have to take into consideration,’ ” the former Minneapolis police official said. “In this case, it’s all there.”

A conviction in Chauvin’s case could encourage prosecutors elsewhere to pursue charges in police killings, experts said. An acquittal or a deadlock, or even a conviction on the lesser counts, could lead to another spasm of unrest. Carter said police nationwide are likely watching the trial most closely for that possibility, given the protests that swept the country after Floyd’s May 25 death.

“It’s a symbolic case in policing,” Carter said. “There are a lot of people who think there are a lot of officers like Derek Chauvin.”

It is unfair, he said, that the case is leading to generalizations about police “because departments are so different and officers are so different across the country.”

Legal experts cautioned against drawing too broad a conclusion from a single criminal case’s outcome, noting that such prosecutions are limited vessels for the larger, structural changes urged by many advocates seeking to reform or defund police.

The accounts put forward by the prosecution and the Minneapolis police chief also seem aimed at drawing the case narrowly around Chauvin, rather than policing in general. In effect, they echo the “bad apple” argument in painting Chauvin as an isolated case.

Critics of police uses of force, however, say the larger issues are more deeply rooted than any single officer in one department. Experts also noted that despite having more than a dozen complaints against him before Floyd’s death, Chauvin remained on the force and was a field training officer overseeing rookies, a key role that helps shape young officers’ approaches to the job.

“Don’t talk to me about bad apples,” Flowers said in a telephone interview. “This is about culture.”