OAKLAND — Regardless of whether the city’s new policy to curtail night protests is even legal, experts say the strategy risks alienating peaceful demonstrators and could undermine years of work to repair relations with Oakland’s fiery activist groups.

Jim Chanin, a local civil rights lawyer with a long history of suing the police for using excessive force, said he wasn’t in favor of Mayor Libby Schaaf’s decision to ban unpermitted night marches from the streets and utilizing a large police presence to force people to the sidewalks.

The city’s change in tactics came after a night of vandalism during the May Day protests earlier this month in which downtown businesses, particularly on Auto Row, suffered thousands of dollars of damage. By keeping crowds confined to the sidewalk, officials theorized, officers could better monitor the situation and stop the city from being trashed.

But Chanin said the policy wouldn’t impact the vandals causing the damage — only the groups interested in peaceful demonstration. Police debuted the policy during a rally last Thursday to recognize black women killed by police across the country.

“This group of demonstrators are not the people causing the damage,” Chanin said. “This will only alienate them … and frankly I just don’t see where this is going.”

The about-face from the city surprised demonstrators, who for years have marched in Oakland’s streets at night without permits, but without repercussion.

It also angered the group, leading to additional downtown protests against Schaaf and the police last weekend in which dozens of people — including a city planning commissioner — were cited or arrested after they refused to be restricted to the sidewalk.

Police advocates hope protesters will learn quickly to adjust to the new rules. But others are concerned the policy could backfire against Schaaf, leading to larger, more violent rallies in the streets as more people try to test the water. Many on Saturday chanted “recall.”

“I respect that there are a variety of feelings about this new practice,” Schaaf said Monday. “Yes, there has been a level of anger, but I believe it is a sensible way of moving this city forward that protects our history of activism.”

And there’s that legal question, too.

City officials argue their strategy is safely legal, but lawyer Rachel Lederman deemed the city’s methods illegal, and she knows more about it than most — she helped write Oakland’s crowd-control rules a decade ago.

Lederman said the National Lawyers Guild hopes to meet with Schaaf and police officials this week. If a resolution doesn’t happen, there’s a good chance the policy could be challenged in court.

Others, like Chanin, isn’t sure whether the practice is legal.

“I don’t know,” he said. “It toes the line. It might be over the line.”

Chanin won a $4.5 million judgment for Scott Olsen after the Iraq War veteran was permanently injured when an officer fired a lead-filled bean bag into his head during an Occupy Oakland protest in 2011.

Police are no longer using such heavy-handed tactics to control crowds, Chanin said, but it doesn’t mean everything is OK. Protesters on Saturday called police “pigs” and demanded the officers leave the area.

“Bottom line is, yes police are using less force, but they’re not improving relations,” he said.

Chanin has no interest in returning to the days of huge crowds and widespread damage, but said vandals interested in causing chaos have an easier time blending into large crowds, breaking off to set fires or break windows.

He understands the city’s frustration with property damage. It bothers him too, he said, but the policy won’t fix it.

“There is no doubt, however, that it’s needlessly provocative against the people that aren’t causing violence,” he said.

Mike Blasky covers Oakland City Hall. Contact him at 510-208-6429. Follow him at Twitter.com/blasky.