Kenneth Carrethers, 43, of Oakland, claims that in retaliation for his comments, the officers kicked, punched and hog-tied him while arresting him at BART's Coliseum-Oakland Airport station on Nov. 15, 2008.
"Officer Mehserle grabbed him for his speech," Carrethers' attorney, Chris Dolan, told the jury in the court of U.S. District Judge Edward Chen during his closing argument.
"People aren't supposed to be beaten by police for exercising their First Amendment rights," Dolan said.
Dolan urged the jurors to "protect the right of people to speak their mind and not get beat up" by ordering a financial award of more than $1 million for Carrethers.
The seven-member civil jury began deliberating at midday after hearing the closing arguments and receiving final jury instructions from Chen.
The incident occurred six and a half weeks before Mehserle fatally shot Oscar Grant of Hayward at BART's Fruitvale station on New Year's Day in 2009.
Mehserle, 29, who said he accidentally used his service gun instead of a stun gun, was later convicted of involuntary manslaughter and served about a year of a two-year sentence.
In the current civil trial, both sides agree that Carrethers used profanities when he passed by officers at the station at 10:30 p.m. and complained they were lazy for having failed to prevent two previous break-ins to his car at the station parking lot.
But they dispute whether he physically threatened the officers.
Carrethers contends he never threatened them, while the officers maintain they tried to ignore him and allow him to "vent," and that Mehserle brought him to the ground only after seeing him raise his hand and appear to be about to strike Officer Fred Guanzon on the head.
BART attorney Dale Allen told the jury during his closing argument, "They had probable cause to place him under arrest when he made the gesture toward striking Officer Guanzon.
"The force was appropriate to the situation," said Allen, who denied that officers kicked, punched or kneed Carrethers while they were handcuffing him and hobbling his feet.
Allen also denied that the officers hog-tied Carrethers by connecting the handcuffs and hobble with a strap, or that they carried him to a police car outside the station by holding the strap.
He said that action would have left handcuff marks on Carrethers' wrists and that no marks or wrist injuries were found when Carrethers was examined in the emergency room at ValleyCare Medical Center in Pleasanton early the next morning.
After being treated at the hospital, Carrethers spent two nights in jail.
He was initially charged with threatening an officer and resisting arrest, but the threat charge was dismissed by a judge, and the resisting arrest charge was dropped two months later by Alameda County prosecutors for lack of sufficient evidence.
Dolan asked that the jury award Carrethers $8,120 in compensation for medical expenses and lost pay, as well as an amount "in the seven figures" for non-economic damages including alleged false arrest, imprisonment, interference with his constitutional rights and humiliation.
Carrethers was on his way home from his job as a San Francisco hotel engineer at the time of the incident.
The seven-figure amount would "send a signal about what is OK in our community," Dolan said.
"He was stripped of his rights and of his humanity as a man," the attorney said.