The man famously detained for eating a breakfast sandwich on a BART platform plans to sue the transit agency for racial discrimination, his attorney said Thursday.

Oakland civil rights attorney John Burris said he filed a claim that precedes suing a government agency in California. He said he will file the lawsuit on behalf of Steve Foster, 31, of Concord if BART officials deny the claim — which is likely.

He declined to say how much money Foster is seeking. BART has 45 days to settle or reject the claim. Burris could then sue the agency in either state or federal court.

A now-viral video captured a BART police officer approaching Foster on Nov. 4 on the platform at the Pleasant Hill BART station and asking him to stop eating his sandwich. In the footage, Foster refuses, continues to eat, and argues with the officer who threatens to take him to jail. Foster leaves in handcuffs. He was later cited but not arrested.

“This case smacks of racial profiling and selective law enforcement,” Burris said an afternoon news conference in Oakland. “It is a situation that could have easily been avoided by an officer who had the good common sense to de-escalate and avoid a confrontation that was of his own doing.”

Eating and drinking on BART platforms and trains is prohibited, though it’s not hard to find someone violating the policy without attracting attention from BART police.

Foster said he regularly eats breakfast sandwiches on the platform while waiting for his train to work. He said he’s never been advised not to eat there. He also said he has never seen anyone else reprimanded, much less cited.

He added he felt intimidated and disrespected, but not necessarily discriminated against at the time.

“At the moment it didn’t feel like it was a whole racial thing,” he told reporters at the Thursday news conference. “I was just confused and upset it was happening. It felt stupid, and still does. It’s crazy.”

Foster said he planned on finishing his sandwich before boarding a train after the officer told him “no eating on BART,” thinking the official was joking. The officer gave him an odd look, he said.

Many people who viewed the video, circulated widely on the Internet late last week, also thought the officer acted unfairly. Some gathered at BART stations to munch sandwiches in protest. BART’s general manager apologized Monday.

The head of BART’s police officers union said the officer acted correctly and that Foster was not only violating transit system policy, but was “hostile and belligerent.”

Burris said he was filing the suit because Foster was a victim of racial profiling.

“These BART officers engaged in racial profiling, and selective law enforcement in that BART patrons routinely eat sandwiches and other food on the platform and BART trains without any law enforcement intervention, chastisement or other admonishments by police,” Burris said.

Chronicle staff writer Alejandro Serrano contributed to this report.

Michael Cabanatuan is a San Francisco Chronicle staff writer. Email: mcabanatuan@sfchronicle.com Twitter: @ctuan