Two classmates at Cheverus High School were roughhousing after school in a parking lot near the athletic fields a little over three years ago.

One of the students, junior Jakob Hammond, put the other, sophomore Patrick Griffin, into a headlock or chokehold.

Witnesses said the interaction seemed innocent enough. Just two teenage boys doing teenage boy things. After a few seconds, Hammond let go. Griffin, though, appeared to lose consciousness. He fell backward, unprotected, hitting his head on the pavement. Witnesses would later say he appeared to experience a seizure.

Griffin spent four days in the hospital, where he was treated for a traumatic brain injury. Three years later, he’s still dealing with the effects, his mother said.

On Monday, in Cumberland County Unified Court, Griffin and attorneys representing his family will try to convince a jury that Cheverus should be held responsible for what happened to him.

“They have never apologized or accepted responsibility for how they handled this,” said Devdra Griffin, Patrick’s mother.

The case against Cheverus, a Jesuit-run private school on Ocean Avenue in Portland, could be a test of how much liability schools should have for the behavior of students, particularly behavior that happens outside of school hours and outside their walls.

Anthony Moffa, a visiting associate professor at the University of Maine School of Law, said it’s unusual to see a case like this make it to trial.

“I think there is probably some risk for Cheverus, at least from a public relations standpoint,” he said.

Cheverus’ attorney, J. William Druary, declined to comment on the case before the trial, but in court filings he has argued broadly that the school cannot possibly be held liable.

The Griffin family had sued the Hammonds as well but settled with them. The terms of that settlement were not disclosed.

The Hammonds did not respond to a message left last week. Their attorney, Elizabeth Stouder, also did not respond to messages.

Bruce Merrill, an attorney for the Griffins, said they discussed settling with Cheverus, too, but the school wouldn’t budge.

The trial is expected to last all week.

IT DIDN’T SEEM SERIOUS, STUDENTS SAID

According to court filings, the incident in question took place on May 18, 2016.

Griffin, who was 14 at the time, and three other students were gathered near the athletic fields watching a javelin competition. Hammond joined them at some point before 4 p.m.

The group walked back toward one of the school buildings, through a parking lot between the fields and the school. During the walk, Griffin and Hammond started horsing around or play fighting, the other students would later say. It didn’t seem serious.

Hammond had Griffin in a headlock – some witnesses described it as a chokehold – and Griffin appeared to be struggling. When Hammond let go, Griffin fell back without breaking his fall.

One of the students immediately called 911. Another went back to the athletic fields to get help.

Griffin was taken by ambulance to Maine Medical Center. He has no memory of what happened, his mother said. She and her husband, John Griffin, were told their son tripped and fell.

At the hospital, Griffin suffered a second grand mal seizure. A scan showed signs of intercranial bleeding. He stayed there four days.

His mother said the incident was scary, but they considered themselves lucky that he wasn’t injured worse. He did, however, miss out on playing interscholastic sports the next year. His mother said that might have derailed his college prospects. He also struggled academically for many months after.

“He’s doing much better now but it’s still something he’s dealing with,” Devdra said of her son, who just finished his first year of college at Roger Williams University in Rhode Island.

CHEVERUS WOULD NOT SETTLE

Griffin’s parents didn’t learn until several days after the incident that their son had been involved in an altercation with Hammond. They wanted to know if he was assaulted and went to police.

Detectives interviewed Hammond and the other students who were there and concluded that Hammond did not intend to harm Griffin. It appeared to be an accident, police said

The Griffins, though, saw it differently. They learned that Hammond had behavioral problems and was taking medication for depression. They questioned whether his parents communicated that to school officials and also whether school officials took any precautions about Hammond’s interactions with classmates.

When the Griffins filed their lawsuit in late 2016, they named as defendants Cheverus, Hammond’s parents (since a minor cannot be sued) and five teachers and administrators at the school who were identified as John and Jane Does.

As the case proceeded, there were numerous motions and depositions of witnesses and experts. At some point, the John and Jane Does were dismissed from the suit. The Griffins then settled with the Hammonds, which removed them from the case.

Devdra Griffin called the settlement satisfactory but would not share any details.

Cheverus would not settle.

Druary, the school’s attorney, said he could not comment on any settlement discussions.

Devdra Griffin, though, said her family wasn’t asking for big sums of money. Just an acknowledgement from the school that it mishandled the incident.

She said she’s less upset about the altercation itself. Boys will be boys, after all.

But she does fault Cheverus for not taking the incident seriously, for not investigating right away and for minimizing her son’s trauma.

“He has a lot of anger toward Cheverus,” she said.

Moffa, the law school professor, said the fight over a settlement could be as simple as Cheverus not agreeing to a monetary amount that might be above what the school’s insurance policy covers. Or, he said, it could be that Cheverus is unwilling to concede any liability even with a settlement.

“There are lots of cases, often in the corporate world, where companies settle without admitting any wrongdoing,” he said.