It's nothing new, really, but there seems to be more unruly fan behavior than ever at American sports events: fistfights in the stands, spitting on players, throwing popcorn and a water bottle at NBA All-Stars, violating COVID protocol, profanity-laced jeers directed at individual players … where does it end?

Here's where it might – sports events played in empty stadiums with fans forbidden from attending. That's nothing new, either, especially in Europe and South America where out-of-control soccer fans ("hooligans") have forced the sport's ruling bodies, including FIFA and UEFA, to punish teams and fans by forcing matches to be played "behind closed doors." Typically this is the last resort against fan violence or racism.

"Behind closed doors" isn't limited to soccer. In 2009, Israel was scheduled to meet Sweden in the first round of tennis' Davis Cup international tournament. The host city in Sweden, fearing anti-Israel demonstrations, pre-emptively announced that the event would be held without fans.

"Behind closed doors" isn't limited to Europe and South America, either. It's happened here. In 2015, a game between the Chicago White Sox and Baltimore Orioles was played without fans at Camden Yards. There was civil unrest in Baltimore following the death of Freddie Gray, an African-American man who was injured while in police custody. The Orioles and city of Baltimore could not guarantee the safety of fans attending the game. Since the game could not be rescheduled for later that season, the teams took the field without fans in the stands. It was an eerie sight in America.

Could current unruly fan behavior rise to events routinely being held "behind closed doors" here? It might, unless something is done now to address unacceptable fan behavior. Teams must strictly strengthen ("enhance") a code of conduct for fans. Perhaps stadiums should designate sections for fans of the visiting team. Family sections with no alcohol sales may be worth considering. Or sections for vaccinated fans only. Anything to lower the temperature in the stands.

Several years ago I was in Rome and bought a ticket from a scalper outside Stadio Olimpico for the big match between A.S. Roma and Juventus. I had never been to a European soccer match, but I had heard wild stories about fans going nuts. This I gotta see.

How was I to know, but my ticket was in the Juventus "supporters section." Enemy territory. The section was partitioned off with bulletproof glass and patrolled by police with automatic weapons strapped on their backs. That didn't stop A.S. Roma fans from tossing chairs and plastic baggies filled with urine over the barriers. The baggies would burst when they hit the ground dousing nearby fans. While disgusting, for an American attending his first soccer match, it was exciting, a story to tell when I got back home. Then again, I wasn't splashed with hooligan urine. Things would have been different then.

A couple of years later, my train from Amsterdam to Paris was delayed for several hours because of soccer "hooliganism." The announcement at Amsterdam Centraal station used that word. This time I was pissed.

A couple of weeks ago, I was in Yankee Stadium for the Astros first games in front of Yankee fans since the Astros cheating scandal broke. I didn't expect Yankee fans to roll out the welcome wagon, but I was surprised when the sold-out crowd (COVID-limited to 10,800) chanted "F-Altuve" and "F-Houston" in unison like a well trained cheer squad. Yankee fans were so hostile that Astros shortstop Carlos Correa, who just last year told critics to "shut the f-up," complained about the jeering.

No problem here. You want to jump and scream at the opposing team, have at it.

I've had a problem with fan behavior only one time. In 2002, I took my son, then 5 years old, to a professional wrestling event. I know, I'm a horrible parent, but I was "working." We were in the 10^th row. In the 11^th row, directly behind us, were five or six guys, I'm guessing in their early 20s, who were yelling graphic sexual insults at the wrestlers, especially the women grapplers. As the evening wore on, the guys got drunker and drunker, and their screams got filthier and filthier and more obscene and racist.

I've been to hundreds of wrestling events, but this was offensive even for wrestling. I'm sitting there with a child, what to do? If I turn and tell them to shut up, they'll tell me where I can go and what I can do when I get there – in front of my kid. I couldn't change seats, the venue was sold out. If I asked an usher for help, well, have you seen the ushers at Houston stadiums? By the time they make it down to the 10^th row, it'll be tomorrow. My only option was to leave. Parents who bring their children to a sporting event should never have to leave because other fans can't behave.

The answer to growing fan violence and offensive behavior is difficult. I know that a fan spitting or throwing something at a player warrants more than simple ejection and banning from future events. Maybe it's time to arrest violent fans and throw them in jail for a few days.

If unruly fans keep it up the only answer may be empty stadiums, and nobody wants that.