Major league players are receiving one-page written reminders this week from their union, as well as MLB management, that smokeless tobacco, aka chaw, is a banned substance in Boston, San Francisco and Los Angeles, including inside their ballparks.

Having spent 10 days walking the streets of San Francisco during Super Bowl week, be assured not all substances are banned there, but I digress.

What one wonders is exactly how will such a ban be enforced inside the Red Sox clubhouse, bullpen and dugout? Has government intrusion come to such a point that members of the ATF will stalk through the dugout examining stained paper cups and trying to match the DNA with Hanley Ramirez?

Stop and frisk might not be a problem on the way to the pitcher’s mound for someone like Clay Buchholz because for some time now, players have been banned from carrying smokeless tobacco tins in their pocket or inside their sock, but would he be subject to a pat-down on the way to the clubhouse or if he’s seen spitting while shagging flies?

As Buchholz and his fellow chewers in baseball go through their paces in Florida and Arizona, they are free to chew whatever they’d like, governmental overreach having not yet regulated the mouths of major leaguers in those states. But Buchholz, be forewarned, Big Brother is watching you with a harder eye than the dental hygienist who keeps staring through you while you’re insisting you really have been flossing twice a day.

“That’ll probably happen,” Buchholz told the Associated Press when asked if he was going to reserve his mouth for only sunflower seeds and Double Bubble this season. “If you get reprimanded for something, there comes a time where you’re tired of paying fines for something you don’t have to do or doesn’t make you any better. You’ve got to obey the rules, or there’s consequences to it. We’ll probably learn more about that when we get up north.”

This raises an interesting point. You go to AT&T Park in San Fran and you can smoke weed in the bleachers without fear of retribution from the local constabulary (although it’s still against ballpark rules). Pop a pinch between your cheek and gum and you’re a law-breaker.

Really?

It seems so because the smokeless tobacco ban in ballparks in those three cities, with more sure to be added soon, applies not only to players but to all other team personnel, umpires and fans. Roll some weed, no problem. Chew some leaf, you’re in handcuffs?

“Major league players are citizens,” commissioner Rob Manfred rationalized last week in Arizona, according to the AP. “Municipalities pass laws. We expect our players will comply with those laws.”

That’s reasonable, but again, how the heck do those municipalities enforce such a ban? They can’t keep the subway running, can’t keep up with deteriorating infrastructure, can’t fill potholes and can’t keep commuter traffic from backing up in every direction, but they’re going to police what a grown man chews and spits into a cup?

Having realized the obtuseness of such an idea, MLB seems to be hinting it’s ready to step in and take the law, and the chaw, into its own hands.

“Please note that these are city ordinances and not rules established by Major League Baseball,” the letter states. “However, the commissioner’s office will be monitoring players and club personnel for compliance with the regulations.”

MLB can’t seem to win an arbitration case against a single player, but it is going to haul the guys in on chaw charges? What will they call it when a player beats their discipline, “The Chawshank Redemption?”

Look, chewing tobacco is among the more disgusting of habits. Users’ teeth turn brown, their breath stinks, and they put themselves at risk of virulent forms of cancer. All good reasons to ban chaw, but there’s another issue here. Don’t you have a right to chew if you choose?

It’s not like we’re talking about second-hand smoke pollution. We’re talking about brown spittle, which you might find offensive, but as a public health issue, it seems like governmental overreach. Is someone really going to bust Buchholz as a scofflaw for chewing tobacco at Fenway Park?

It’s a bad habit. It’s unhealthy. It’s something you don’t want your kids doing. But if that’s your concern, police what your kid puts in his mouth. Don’t try to have saliva police lurking around Fenway Park enforcing an unenforceable ban.

If they do, our government really has gone nuts. If they don’t, then what’s the point of the ban in the first place?

Here’s a better suggestion for Boston, San Francisco and L.A. How about making sure our bridges don’t fall down on top of us while we’re stuck in traffic polluting the atmosphere because we’re all moving four miles an hour?

If they can do that, what some guy in knickers and high socks is spitting really seems to be his business, not a city’s.