It took about 30 seconds after Thomas Gaither sat down at a whites-only lunch counter for police to shove him to the ground, handcuff him and march him over to jail.

It took a day for a judge to convict him and eight others, sending them to prison for a month of hard labor.

And it took 54 years for the state of South Carolina to officially say that what happened was wrong — wiping clean the record of Mr. Gaither of Prospect, Butler County, and the other members of the “Friendship 9” at a packed hearing Wednesday.

“We cannot rewrite history, but we can right history,” Judge Mark Hayes said as he made the ruling, to claps and cheers from the courtroom in Rock Hill, S.C.

Mr. Gaither watched the hearing on national television from his home. Due to his wife’s health, he was unable to travel to the South Carolina hearing, sending his son and a nephew instead.

But for the 77-year-old retired Slippery Rock University biology professor, it was a gratifying day.

“I am grateful that it’s no longer a part of my record,” he said, sitting next to his bubbling fish tank with newspaper clippings scattered across his dining room table. “It’s not why we did what we did, but it does show we’ve made progress.”

In 1961, Mr. Gaither was a field secretary for the Congress of Racial Equality. To commemorate a year since the Feb. 1, 1960, sit-in at a Woolworth’s lunch counter in Greensboro, N.C., he recruited eight students at Rock Hill’s Friendship Junior College to order a hamburger from McCrory’s variety store in Rock Hill with the intention of sitting down to eat it.

African-Americans at the time could order food from McCrory’s but had to eat it elsewhere.

Within seconds of sitting down, the men were arrested. They were convicted of trespassing and sentenced to either pay a $100 fine or serve a month of labor at a prison camp.

On principle, the men opted for the jail time. “This was the start of what would become known as the ‘jail no bail’ phase of the modern civil rights movement,” Mr. Gaither said. “It didn’t make sense to violate the law and then put money right back into the system.”

Demonstrators across the South adopted that tactic, filling jail cells. The media attention helped turn scattered protests into a nationwide movement.

Mr. Gaither proudly handled a copy of “No Fear for Freedom: The Story of the Friendship 9” across his dining room table — a children’s book published last year by author Kim Johnson. After writing the book, she went to Kevin Brackett, the solicitor for York and Union counties, to see what could be done to clear their records.

In court Wednesday, Mr. Brackett apologized to the men present: “Sometimes you just have to say you’re sorry … My heartfelt apologies for what happened in 1961,” he said.

For a month, Mr. Gaither and the others were awakened at 6 a.m. for a day of shoveling sand into trucks — labor that they thought was serving a public works purpose but later found out was just busy work. At any time, they could have paid the $100 fine to be released.

“The idea was to work us so hard that we would have second thoughts,” he said. At one point, a cross was burned on the lawn of Mr. Gaither’s parents’ home, who lived 30 miles away in Orangeburg.

After a month — some of which was spent in solitary confinement — the men were released.

Mr. Gaither continued to work for CORE, organizing a Freedom Ride that was supposed to go to New Orleans but got stopped by violence in Anniston, Ala.

He went back to school for his master’s degree at Atlanta University and Ph.D. from the University of Iowa. His “first and only job” was as a biology professor at Slippery Rock specializing in botany, where he taught for nearly four decades until retiring in 2007.

In Rock Hill on Wednesday, the men who attended the hearing took a trip back to the site of what was once McCrory’s. Their names are now engraved on the stools at the counter of the restaurant on Main Street, now called the Old Town Bistro. A plaque outside marks the spot where they were arrested.

Mr. Gaither hopes to soon take his grandchildren to visit, to share his experiences with them.

“I learned that I have causes that I am willing to suffer for,” he said, “to make sure things are more just and fairer for all of us.”

First Published: January 29, 2015, 5:00 a.m.