Defense lawyers submitted this video as evidence in California’s criminal case against the skateboarder Jesse Vieira. He pleaded not guilty and claimed self-defense.

Defense lawyers submitted this video as evidence in California’s criminal case against the skateboarder Jesse Vieira. He pleaded not guilty and claimed self-defense.

Skateboarders have long glorified confrontations with security workers. This one led not only to a life-altering injury, but also to soul-searching in a sport about to have its Olympic debut.

The open area outside 555 California Street in San Francisco is known as Black Rock to skateboarders, who turned this otherwise unexceptional corporate plaza into a magnet for the sport beginning in the 1990s.

With its low, stone walls and steps lined with steel banisters, the plaza has served as an ideal stage for the skateboarding videos that proliferate on the internet, attracting skaters from across the region to a spot where skateboarding is prohibited.

In November, a group of skaters descended upon the plaza. Within minutes, a security guard who had worked at 555 California for 12 years, Dan Jansen, arrived to shoo them out, moving steel barriers in front of the area where the skaters wanted to do their tricks.

Just as quickly, skaters removed the barriers, and an increasingly tense show of force from both sides ensued. At one point, Jansen picked up a skateboard and tossed it into the street. That is when the situation turned violent. Within seconds, he was lying unconscious in a pool of his urine.

Security footage shows the confrontation between skateboarders and a security worker outside 555 California Street in San Francisco, known as Black Rock.

The confrontation was captured by a security camera a short distance away. The trauma to Jansen’s head caused his brain to swell, requiring emergency surgery to remove a part of his skull and frontal lobe. “All medical teams agreed that without surgery, this patient will die,” read one of Jansen’s health records. He was left with permanent brain damage.

Nearly nine months later, he still struggles with walking and recognizing family members.

Dan Jansen in a photograph provided by the family. Amanda Jansen

For the skateboarding world, which for years has glorified disputes with security guards, the confrontation has resulted in collective soul-searching at a crucial moment, just a year before the sport’s Olympic debut at the 2020 Games in Tokyo. A sport that has long identified with rebellion is questioning whether its fascination with defiance is somehow responsible for forever changing the life of someone simply doing his job.

“I do hold those who glamorize confronting security — rather than just leaving the second we are asked, as 99 percent of skaters do — somewhat responsible for the behavior they depict and profit from,” said Mackenzie Eisenhour, a former editor of Transworld Skateboarding, which has featured videos of security confrontations on its website.

But was it self-defense? One jury could not break a deadlock on that question. Another will hear the case in the coming months.

A confrontation like the one at 555 California would never have happened had skateboarding not moved, beginning in the 1980s, away from the parks and ramps built for the sport. Skateboarding now largely exists in a legally hazy space where amateur and professional skateboarders use existing infrastructure for their own purposes. Skateboarders, photographers and filmers now scout locations to document their tricks, creating a world with its own code of behavior, including an unspoken prohibition against executing the same trick at the same location as a previous skater.

That code never addressed how to respond when security workers do their job. Some skateboarders choose to flee before anything escalates, but others engage, often making for compelling scenes of what goes into the act of creating these videos.

A clip posted to Thrasher magazine’s Instagram account days before Jansen was injured shows a skater crashing into a security guard not far from 555 California Street.

Jansen had dealt with skateboarders many times before. The previous day, a colleague had called the police because of a resistant group of them.

“There’s 10, 15 skateboarders on the property, on the sidewalk,” the colleague says on a recording. “And we’ve asked them to leave and they’re not, and it’s getting out of hand. ”

On Dec. 10, the police in San Francisco arrested Jesse Vieira, a professional skateboarder, in connection with the confrontation with Jansen. Vieira was charged with assault with a deadly weapon, assault with force likely to cause great bodily injury and battery with serious bodily injury.

He pleaded not guilty and claimed self-defense. In May, a jury deadlocked. Prosecutors have set a new court date for September.

A lawyer for Vieira, Doug Rappaport, said the altercation and Jansen’s injury were the result of a series of unfortunate events. He said Jansen overreacted in the heat of the moment.

“Everything just came to a head that day and he just lost his cool just for a split second and Jesse happened to be standing there,” Rappaport said. “It’s unfortunate for everybody, horrible for the security guard.”

Jansen’s family is less focused on the outcome of the trial than on his struggles with the injuries.

“What happens to Jesse doesn’t change anything,” Amanda Jansen said when asked how she felt after the mistrial.

Regardless of the outcome of the next trial, some important voices from within skateboarding are acknowledging that the sport needs to put the brakes on glorifying conflicts with security workers and get back to what Eisenhour described as “certain guidelines” that can minimize “the odds of conflict — and keeping the disruption to a minimum so the spot can still be used by others.”

If this case is an example, those guidelines may have broken down over time.

Brian Anderson, a longtime professional skateboarder and Thrasher’s 1999 skater of the year, said there were ways to head off a conflict.

“Sometimes there will be a security guard that’s like, ‘Hey you guys, I didn’t see you, you didn’t see me,’ and he or she will actually leave and you say thanks,” Anderson said.

Other times, skating involves moving from one place to the next to stay one step ahead of trouble.

“Treating those people with respect and walking away provides you with the opportunity to just feel better, feel good about yourself, but also you can most likely come back,” Josh Stewart, who makes films about the sport, said.

Since the inception of skateboarding, many skateboarders have sought the image of being rebels in an outlaw sport in which dodging security guards and the police goes with the territory. In the 1970s, skaters would find foreclosed homes and skate in their empty swimming pools, quickly fleeing if somebody came.

Once street skateboarding became dominant, videos that celebrated altercations with security guards, homeowners and pedestrians began to proliferate.

Neal Mims, a former professional skateboarder, said the rebellious side of skateboarding was always present. He said he did not like it because it was disrespectful to those outside the sport.

Neal Mims from Transworld SKATEboarding's Feedback video released in 1999. Transworld SKATEboarding

In a 1999 clip from the Transworld Skateboarding video “Feedback,” Mims nearly crashed into an oncoming security worker, and then got into a verbal altercation.

Mims, now a skateboarding coach, said skaters still recited the dialogue to him, though he was now ashamed of it. “The words, the language that I used, all is very disrespectful,” he said. “Pointing my finger in his face, telling him this ‘thing will annihilate you.’”

In 2018, around the time of the confrontation at 555 California Street, the skateboard shop and streetwear brand Supreme released a video called “Blessed.” In the final section of the video, the skateboarder Tyshawn Jones was shown trying to wrestle a security worker’s bicycle away from him and to tear barriers from a security worker’s hands in order to do his tricks. Later in 2018, Jones was crowned Thrasher’s skater of the year.

“I do believe that having Supreme, then Thrasher, elevate and glamorize that behavior to their highest rungs can lead to bad things as kids copy it in real life,” Eisenhour said. “To a degree, we are all guilty.”

Jones declined to comment. Thrasher did not respond to requests for comment.

For two weeks, there was no official word about who was involved at Black Rock, but the police suspected skateboarders, according to news reports. The security footage the police were using to identify suspects clearly showed a group of seven skateboarders.

The first post on the Slap message boards about the confrontation was dated Nov. 27, 2018.

Online message boards speculated that the altercation might have involved a crew of skateboarders calling themselves GX1000, who had become well known among skaters for their raw street skating and altercations with pedestrians, homeowners and security guards. The name GX1000 is trademarked by High Speed Productions, the owner of Thrasher. They have also been featured in The New York Times.

The charges against Jesse Vieira.

Vieira, the defendant, was recently on the cover of Thrasher and is a staple of the GX1000 videos. This was not a rogue gang with skateboards. This was a group of professionals with support from companies that embraced the sport’s culture.

Jesse Vieira on the cover of the August 2018 issue of Thrasher magazine.

During the trial, defense lawyers presented a second video of the confrontation, shot by one of the skateboarders at the scene. Vieira’s lawyer has argued that Jansen was responsible for inciting the violence.

Defense lawyers submitted this video as evidence in California’s criminal case against the skateboarder Jesse Vieira. He pleaded not guilty and claimed self-defense.

Still, numerous skateboarders described a sense of embarrassment to be associated with such behavior.

A Jan. 4, 2019, Instagram post from Eisenhour brought the story to the attention of many skaters.

The longtime skateboard photographer Bryce Kanights responded to the post, writing: “Truly saddened to see this and disgusted to think that those that enjoy the freedoms of skateboarding had to take such violent forms of action against a person doing their job.”

Stewart, the filmmaker, said he was worried about repercussions for the sport. If the sport glorifies confrontations, security workers may crack down even harder, limiting the places to skate.

Suggesting the culture needs to do its own policing, he said, “When I see it in videos it confirms to me or confirms to the rest of the world that it’s something that needs to be more policed.”

Jansen being transferred to a walker for rehabilitation in June. Amanda Jansen

Jansen has had two additional brain operations. For a time, he was able to walk with assistance, but not anymore. He had recovered enough to recognize family members, but that ability has also declined. He currently receives therapy in outpatient rehab five days a week, but the arrangement is temporary, and his long-term future remains uncertain.

“We will need to figure out how to care for him,” Jansen’s niece, Amanda, said.

Vieira’s lawyer insisted in the first trial that Jansen had a longstanding resentment toward skateboarders, that he referred to them as “punks” and “street brats” to his boss.

“Security guards don’t have the right to beat you, and that’s what happened here,” Mr. Rappaport, the lawyer, said. “It’s so sad, but the fact is, it was a fight — and Mr. Vieira defended himself.”

Whether or not a second jury agrees with him, the skateboarding community will render its own judgment.

“I think the skate culture needs to take a long, hard look at where it’s going,” the Berrics, a skateboarding website, posted on Eisenhour’s Instagram post. “This is really sad for anyone to have to deal with.”