A man yells at police in riot gear in University City, Mo., in September. (Jeff Roberson/Associated Press)

This is a pretty big deal:

A federal judge on Wednesday placed restrictions on the St. Louis Metropolitan Police Department, saying their conduct during recent protests had violated demonstrators’ constitutional rights.

U.S. District Judge Catherine Perry ruled that the plaintiffs in a lawsuit against St. Louis police “are likely to prevail on the merits of their claims” that their First and Fourth Amendment rights were violated.

The protests in question took place in September, following a “not guilty” verdict in the murder trial of Jason Stockley, a white former police officer who in 2011 shot and killed Anthony Lamar Smith, who was black.

Perry found sufficient evidence that police arbitrarily declared an assembly unlawful even when there was no violence, and that there was “no credible threat of force or violence to officers or property” when police rounded up citizens, including journalists, on Sept. 17. After those arrests, the acting head of the St. Louis MPD declared that his department had “owned” the night, as his officers mocked protesters by chanting “Whose streets? Our streets!”

Perry also said that officers had clearly retaliated against protected First Amendment speech because they didn’t like being criticized, and used chemical weaponry to suppress speech they didn’t like.

This seems to jibe with firsthand accounts of the protests. Police made mass arrests that swept up journalists, onlookers and even a black undercover officer, who was reportedly beaten. This also seems like one of those “How would we view this if it happened in another country?” moments. A judge just found the police guilty of using chemical agents on protesters because those protesters were criticizing the police. You can read the opinion itself at the above HuffPost link.

The disheartening takeaway here is that St. Louis County police seem to have learned nothing at all from Ferguson. When a protest begins, they’re still responding out of the gate with an overwhelming show of force. They’re still portraying protesters as the enemy, instead of citizens with rights that the police are obligated to protect. They still clearly see their own role as not facilitators of First Amendment rights, but as the countervailing weight when citizens choose to exercise those rights.

I don’t doubt that it’s difficult to be a cop assigned to one of these protests. I’ve seen the videos. I’ve seen the protesters screaming, taunting and insulting cops. But that’s also part of the job. Your job is to not take it personally. The job is to continue to serve and protect — and that includes those people who you think aren’t particularly grateful for it. That “Our streets” chant, the indiscriminate arrests and use of pepper spray, the mass show of force, the utter arrogance of the department leadership — none of that is going to make the job any easier. It’s all just more fuel for the fire. It means less trust in police to fairly and impartially investigate the next shooting. It means less deference to police authority, even for orders that may be perfectly lawful and reasonable. It means more anger when the next protest fires up.  The police are the state actors here. They’re the public servants. It’s up to them to win back the public trust. When you arrest and beat one of your own, and then try to claim that the undercover cop was “resisting,” you’ve lost all credibility.

It’s time for contrition, for some magnanimity. That can only start at the top.