(Reuters) -A judge in Atlanta said on Tuesday he would dismiss racketeering charges against all 61 people accused of a criminal conspiracy for their roles in trying block construction of a police training center they derisively dubbed "Cop City."

Speaking from the bench at a pretrial motions hearing, Fulton County Judge Kevin Farmer said he agreed with defense lawyers that the state attorney general brought the racketeering indictment without proper authority, various news media reported.

Farmer said the attorney general's office had failed, as required, to obtain written permission from the governor, Brian Kemp, to prosecute a case under the state's Racketeer Influenced and Corrupt Organizations Act, according to the Atlanta Journal-Constitution.

The Georgia state constitution limits the authority of the attorney general's office to pursue criminal cases in state court in lieu of local prosecutions.

"At this time, I do not find the attorney general had the authority to bring this RICO case," Farmer was quoted as saying. "The mechanisms were in place, and the steps just weren't followed."

The ruling could deal a political blow to the attorney general, Chris Carr, who is seeking his party's nomination to succeed fellow Republican Kemp in next year's gubernatorial election.

Deputy Attorney General John Fowler, who was leading the prosecution for the AG's office, said if Farmer made good on his stated intention to dismiss the racketeering charges, the state would appeal.

Farmer indicated he also would toss out arson charges facing five of the defendants on a similar technicality but was inclined to let separate domestic terrorism charges stand against those same five individuals.

Defense lawyer Michael Schwartz told the Journal-Constitution the defense planned to work with Farmer and the AG's office on next steps.

The defendants, self-described social justice activists and environmentalists, had fiercely opposed construction of the $90 million Atlanta Public Safety Training Center on an 85-acre (34-hectare) wooded site.

The group said the project, which has since been built and opened, would increase militarization of the police and destroy a forested area they called the "lungs of Atlanta."

The 61 defendants were accused under the RICO Act, a statute typically used against organized crime, of engaging in various offenses as part of an "extremist" criminal enterprise to interfere with the construction project.

Over a two-year period, members of the Defend the Atlanta Forest movement sought to stall the project by erecting barricades and building makeshift treehouses they occupied on the property.

Confrontations with authorities boiled over in March 2023 in what court papers described as a riot, with violence ultimately leading to the fatal shooting of a protester by police.

A state investigation found that the protester had opened fire on police from his tent, wounding one officer before police returned fire. The protester's family disputed the findings, saying Manuel Paez Teran, 26, had his hands raised when he was shot 57 times.

(Reporting by Steve Gorman in Los AngelesEditing by Shri Navaratnam)