In the months after he was officially banned for life from the old Giants Stadium in New Jersey in 2003 for some generally loutish behavior – which included pouring beers on and throwing punches at some opposing fans — Gabe was tempted at least once to risk arrest by defying the ban. But despite his proven penchant for impulsive behavior, this time he thought better of it.

“I’m pretty sure that if I put on a different hat [and] different jersey and behaved they wouldn’t see me,” said “Gabe” – not his real name — who spoke about his experience on the condition of anonymity. “But I didn’t really want to test it.”

Most times when a fan is banned from a stadium, whether for running onto the field, fighting in the stands or some other offense, the process is simple, quick and more or less invisible to the public. The offending fan is taken to a holding room inside the stadium and made to sign a document agreeing to the ban. Photos are taken and are distributed to stadium ushers and security personnel in case the banned fan decides to test his luck. The games go on.

But this week brought one of the most visible and infamous cases of bad fan behavior in recent memory. On Tuesday night during the American League Wild-Card Game at Toronto’s Rogers Centre, a Blue Jays fan – whom police have identified as Ken Pagan, a copy editor for a Toronto media organization – threw a full beer can at Baltimore Orioles left fielder, nearly striking him as he made a catch near the warning track.

Pagan, 41, turned himself in Thursday night and according to the Toronto Police Service was charged with mischief. He is scheduled to appear in court for the first time Nov. 24. Pagan almost certainly will be banned from Rogers Centre for life, and in his case, there has been enough widespread publicity to ensure he would be spotted in the event he tried to defy the ban.

But in the majority of cases, a lifetime ban is inherently difficult to enforce, according to stadium and team officials who deal with those cases. And no one knows for certain how many times a banned fan has managed to get back in.

“There are problems associated with trying to prevent that person from getting back in,” said Rick Nafe, vice president of operations and facilities for the Tampa Bay Rays. “We can take pictures and get them out to the [entrance] gates and let security know they’ve been banned. But is it infallible? Absolutely not … It can be easy as turning your T-shirt around and putting on a hat.”

William D. Squires, former stadium manager and vice president of Yankee Stadium, Cleveland Browns Stadium and Giants Stadium, said he would station undercover security personnel, some of them wearing jerseys of the opposing team, in the stands to be on the lookout for banned fans suspected of trying to gain entry.

“The challenge you have is that people who get themselves ejected from a stadium probably did something very stupid, and it doesn’t make them any smarter the next day,” Squires said. “They figure, ‘Well, I’ll just come back in.’ [But] if someone is banned, and they gain entry, now they’re getting arrested for trespassing.”

Gabe, the fan ejected and banned from Giants Stadium in  2003, said he was made to sign a document, which he did without reading it, and was photographed holding it – generally speaking, a statement acknowledging the offense and the subsequent ban. Gabe said he was told he was banned from the property and would be arrested for trespassing if he returned.

In the NFL, beginning in 2015, a fan banned from one stadium is banned from all NFL stadiums; the league shares information between teams through a centralized database and hired a technology and security firm to assist with the effort. Major League Baseball has not instituted a similar universal ban, though it has shared information with teams when a problematic fan has caused trouble in multiple stadiums.

At Nationals Park, where the Washington Nationals opened their 2016 postseason on Friday, local ordinances do not allow the team to ban an unruly fan for life – the maximum is five years, according to Frank Gambino, senior vice president of ballpark operations. He estimated that such a ban is invoked somewhere between four and six times per season on average.

Asked what behaviors warrant a maximum banishment, Gambino said, “If you jump on the field [and] disrupt the game, yes. If you tried to injure a player, yes. If you got in an altercation [in the stands], you wouldn’t necessarily be arrested unless someone pressed charges, but you would be ejected and possibly banned.”

But keeping banned fans out of the stadium remains the tricky part. In the case of the Nationals, like many teams, the team does a standard check to see if the fan in question has any tickets already purchased for upcoming games using the same credit card, in which case those tickets are canceled. However, Gambino was not sure whether future tickets purchased with the same credit card would be flagged by the ticketing department.

A banned fan can always get a friend to purchase a ticket for him, of course, but in that case the friend is legally responsible and can be punished if caught.

“That’s part of the standard ticket policy printed on the back of every ticket,” said Mark Burk, director of the University of Utah’s Rice-Eccles Stadium and president of the Stadium Managers Association. “To my knowledge, at almost all stadiums, the ticket holder is responsible for the person who actually uses the ticket. If they give their ticket to someone who has been banned, it violates the fan policy, and that season ticket holder could lose their season-ticket privileges.”

Advances in technology have made it easier to identify particular fans once they are inside the gates, as was the case with Pagan, who was ID’d in part by footage from television and security cameras.

But the Holy Grail of crowd management – facial recognition software, of the type currently in use by many federal agencies at airports and other secure venues – is still years away from widespread deployment at stadiums and arenas.

“I don’t think anybody has facial recognition technology actively in use, but it’s something that’s feasible. We’ve seen tests of that,” said Joe Abernathy, vice president of stadium operations for Busch Stadium in St. Louis and a former president of the Stadium Managers Association. “We have camera systems in the right places, and we’re watching fans as they enter the park. We don’t have facial recognition capabilities, but it’s definitely coming.”

In Gabe’s case, it is unclear whether the ban from Giants Stadium extended to MetLife Stadium – which replaced its now-demolished predecessor in 2010. Squires, the former Giants Stadium manager, said there were some transfer-of-power policies in place at the time to govern the changeover, but he was unsure whether such bans were included.

Either way, Gabe isn’t taking any chances.

“My understanding was that it applied only to that stadium – but it was for any event, not just a [football] game,” Gabe said. “But now that the stadium is gone, I should be fine. I still haven’t tried, because I don’t want to be arrested. I’ve got a career now, and that’s not something I’m really looking to do.”