Former Los Angeles police officer Rebecca Reyes took a picture of an evidence photo and the image ended up on celebrity website TMZ, although she denies that she sent it to the site.
Reyes snapped the photo to show to other officers and acquaintances, court filings state.
The image was one of several taken by police officers investigating Brown's February 2009 attack on Rihanna, whose real name is Robyn Fenty.
Superior Court Judge Luis A. Lavin issued a ruling agreeing with the decisions of a disciplinary panel and Police Chief Charlie Beck to fire Reyes in 2012. After reviewing the record, Lavin also concluded that evidence supports that Ryes "participated in the release of the photography showing Ms. Fenty's injuries to TMZ."
The judge said he agreed that Reyes should no longer be a police officer.
"At a minimum, the public is entitled to protection from unprofessional employees whose conduct places people at risk of injury and the government at risk of incurring liability," Lavin's wrote in his ruling.
Reyes' attorney Ira Salzman accepted the ruling without argument during a brief hearing Thursday. He said after the hearing that he was disappointed by the ruling and reiterated that his client did not leak the image to TMZ. He disagreed with Lavin's descriptions of his client as unprofessional, saying she "made a singular mistake."
"Rebecca Reyes is an outstanding person and was an outstanding officer," he said.
Reyes had been an officer for 10 years before she was fired. In the hours after the Rihanna attack, Reyes was assigned to a team planning to arrest Brown but was pulled off the assignment. She saw an evidence photo of Rihanna's injuries at her precinct and snapped a photo to share with others, including a former girlfriend who records show called TMZ.
The ex-girlfriend, also a Los Angeles police officer, told investigators she called the celebrity news site only to verify details of the attack that Reyes shared with her.
Salzman said Reyes' ex-girlfriend, Blanca Lopez, remains on the force and that the person who leaked the photo "has never been found and never will be."
Reyes and Lopez were in the midst of a breakup when the photo was leaked and both were investigated for their actions. Search warrants found no evidence of payments to either woman by TMZ, or conclusive proof of who gave the site the image.
Brown is currently in a Los Angeles jail held without bail after he was arrested March 14 for failing to remain in rehab as ordered by a judge. The rehab stay was part of his sentence for the Rihanna attack and his guilty plea on a felony assault charge.