Already a hot-button issue in the United Kingdom, a controversial bookmaking practice is starting to spread in the U.S.'s growing legal sports betting market, too.

Bookmakers from London to Las Vegas are refusing to take bets from a growing number of customers whose only offense might be trying to win.

The full scope of the issue in the U.K. is difficult to determine, but it's believed only a small fraction of the roughly 8.5 million "punters" (the European term for bettors) are impacted. Gaming experts say sportsbooks might have closed as many as 50,000 betting accounts in recent years, and just as many punters have had their betting limits restricted to mere pittance.

As one U.K. bettor put it, "If you try to win, they don't let you play anymore."

"Yes, bookmakers are severely restricting or closing accounts for what appears to be the fact that these people are winning," said U.K. gambling consultant Steve Donoughue, secretariat for an all-party parliamentary group that focuses on gaming.

"The hilariousness of it," Donoughue added, "is that they restricted one of my member's accounts, and he's a Lord."

The profit-minded corporations that have entered the bookmaking game, however, look at it from the perspective of their bottom line and wonder what business would ever choose to cater to customers thought to be "uneconomical." It's like encouraging a world-class competitive eater to dine often at your all-you-can-eat buffet.

American sports betting is not immune to the practice. Banning or limiting sophisticated players has been a regular part of Las Vegas sports betting for decades, and, like in the U.K., there's absolutely nothing illegal about it.

Bettors say the practice is increasing and has even occurred in some of the new states (such as New Jersey) that have entered into the now-legal bookmaking game in recent months.

"Americans should be worried," said Brian Chappell, a founder for the U.K. bettor advocacy group Justice for Punters. "It's coming."

A reputation for sportsbook giant William Hill

In Nevada, refusing to take bets from any customer, from card counters to wise-guy sports bettors, is completely within any casino's legal rights. From Caesars Palace to the Venetian to more local spots like Station Casinos, every bookmaker in town will tell you -- albeit somewhat quietly -- that they've 86'd customers for one reason or another.

Seasoned bettors are concerned, though, that the practice of banning or limiting accounts is not only increasing, but the reasoning behind the decisions is becoming more and more suspect.

Many believe that the only thing betting intelligently will get you at some shops is a one-way ticket to being thrown out. An iconic U.K. bookmaker that's rapidly growing its footprint in the U.S. is said to be by far the most aggressive with the tactic.

ESPN communicated with 20 bettors for this article who said they had been banned from betting with William Hill U.S. in Nevada. Two said they already have been cut off at the new William Hill books in New Jersey, too, something the Division of Gaming Enforcement is reviewing.

"In our world, our community," said Joe Fortuna, one of the professional bettors who says he was cut off by William Hill in Nevada, "everyone knows you'll get thrown out of there."

"It's not even really close," said another Las Vegas bettor who had been restricted by William Hill and requested anonymity. "They're by far the worst."

Founded in 1934 in London, William Hill was granted a Nevada gaming license in 2012. The company has grown into the largest bookmaker by volume in Nevada, serving more than 100,000 customers and operating in more than 100 locations -- including at casinos like Casino Royale and Hooters on the Las Vegas Strip. They have the most customers and, in turn, probably have the most complaints directed at them.

A vast majority of William Hill's customers are recreational bettors who wager small amounts and never test the limits, house rules or gaming regulations. Industry sources say it's the remaining sliver of bettors who make the book uncomfortable enough to eliminate some of them from the equation.

William Hill has a reputation of banning bettors in Nevada and the U.K. Danny Lawson/PA Images/ Getty Images

William Hill executives make the decision on which accounts to shut down during a weekly meeting in the Las Vegas corporate office, according to multiple sources familiar with the company's practices. In these meetings, often held on Wednesdays, CEO Joe Asher will scroll through a list of accounts, flagging any that stand out as potential threats. He will then ask his team of traders why they should continue doing business with these customers.

The traders, sources said, regularly resist, promising that a player ultimately will lose back all their winnings and then some. Their resistance, however, has not prevented hundreds of bettors from being put on a list that prohibits them from betting with William Hill in person or on the company's mobile app. "I would be surprised if it's not in the thousands," one industry source said.

William Hill says the bettors on the banned list belong there. Nevada bookmakers are heavily regulated and risk federal scrutiny as well as six- and even seven-figure fines from Nevada Gaming Control if they don't maintain anti-money laundering and know-your-customer protocols. If a bettor is found to be unsuitable and violating federal law or state regulations, the bookmaker who took their bet is often held responsible too. To stay in good standing with regulators, licensed operators must be careful.

Anyone named in illegal gambling investigations is put on William Hill's banned list, along with bettors suspected of sharing accounts on the mobile app, a violation of gaming control regulations.

There is, however, a select group of bettors, dozens of them, who insist they haven't done anything except try to place smart bets and yet were still cut off. Some are angle-shooting advantage players, who target oddsmakers' mistakes and any latency in updating the lines, while others on the list say they are simply avid sports bettors who try to play the best odds. All kinds have been shown the door at William Hill, according to the bettors and additional industry sources.

"It is completely false to say that we ban people simply for winning," William Hill U.S. told ESPN in a statement. "There are literally tens of thousands of customers in Nevada that are winners at William Hill. That's one of the great things about sports betting -- a lot of customers do win.

"In the rare situation where we do prohibit someone from wagering with us, there are a variety of reasons why. They include the sharing of accounts (usually tied to someone who previously has been banned), betting on behalf of third parties, screen scraping and other efforts to 'game' the system, as well as compliance reasons or being offensive to staff and/or other customers.

"If someone tells you that the reason that they are prohibited from wagering with William Hill is because they are winning, they are not telling you the whole story."

The company declined to answer further questions on the record and did not respond to follow-up requests to clarify the meaning of "screen scraping." Several bettors said they weren't certain what "screen scraping" entails.

At ESPN's request, bettors provided emails and screenshots from their mobile accounts that notified them they could no longer bet with William Hill. Some bettors said they were even in the red overall at the book, but might have had a recent hot streak or won on a long-shot futures bet that preceded their being cut off.

It happened to Fortuna two years ago. After cashing a winning bet on the Golden State Warriors in the NBA Finals, he went back to the William Hill book the next day and was told he was no longer allowed to bet.

"They don't give you any reason," Fortuna said. "We called corporate and didn't get anywhere. It's almost like they're saying, 'We don't have to serve you,' which is unfair. You can't win. It's not really bookmaking."

Another bettor was informed of his banishment via email: "While we appreciate your previous business, the company has decided to no longer conduct business with you," a William Hill representative wrote.

The bettor said he sent three follow-up emails and left multiple phone messages asking for a reason for the decision but never got a response.

How other Nevada sportsbooks operate

Some professional bettors have accepted that the books' right of refusal is just part of the cost of doing business that comes along with their chosen career. Some bettors said they go to great lengths to try to stay off the radar. They'll keep their bets under the limits and will even intentionally place wagers at less-advantageous odds.

"My personal experience here is that they have not backed me off," said Ed Miller, a Las Vegas-based sports bettor and accomplished poker author. "I have won here in Nevada. I know other people who have won. If you don't want to get backed off, you've kind of got to play it on their terms a little bit."

Not every sportsbook in Nevada takes a hardline approach to dealing with sharp bettors. Some Vegas veterans believe it is part of their responsibility as a bookmaker to accept decent-size wagers -- anywhere from $500 to $2,000, for example -- from any bettor in good standing. Some even welcome wiseguys, to an extent.

The Westgate Las Vegas SuperBook divides bettors into eight categories, based on how sharp they are perceived to be and previous betting history. Ethan Miller/Getty Images

"We like having wise-guy action," said Chris Andrews, sportsbook director at the South Point Casinos and a nearly 40-year Nevada bookmaker. "You can use their information if you manage them properly, and it will help your bottom line."

Ed Malinowski, sportsbook director for The Stratosphere, divides wise-guy action into two categories: handicappers who bet their opinions, and advantage players who might place arbitrage bets on both sides of games and target off-market lines and odds.

"The advantage players are the ones who are just scalping prices and taking advantage of weak numbers," Malinowski said. "Those are more of the undesirable-type players we don't want in here."

The Westgate SuperBook, which is known to accept sharp action, creates a profile on every bettor in its database. Similar to The Stratosphere's practice, the SuperBook places bettors in eight different categories.

"We categorize them from the sharpest of the sharp -- the guys who bet their own opinions and we respect greatly -- to your average Joe," said Jay Kornegay, vice president of race and sports for the SuperBook. "We get a lot of sharp players in here that we deal with on a daily basis. We monitor them very, very closely. We profile to a point where we know exactly what they're doing and mold their limits accordingly."

In the end, you have two professions, each trying to increase profits, but only one side gets to make the rules.

"It's a cat-and-mouse game with these guys," added Malinowski, a 25-year-plus Nevada bookmaker. "Obviously, they're doing their job, and we're trying to do ours."

'A business, not a public service'

The crux of the debate can be boiled down to two quotes from a January seminar in the U.K., hosted by the Parliamentary All-Party Betting & Gaming Group titled, "Are Bookmakers unfairly closing customer accounts?"

During the meeting, members of Parliament listened to industry stakeholders, including bookmakers and punters, state their cases.

"Risk management should not be taken to equal risk elimination," said Simon Rolans, chairman for a horse racing bettors advocacy group. "Betting on horse racing, by its nature, involves risk -- whichever side of the counter you are on -- and that is a significant part of its appeal compared to some alternatives."

Richard Flint, CEO of U.K. online bookmaker Sky Betting & Gaming, spoke next.

"We are ... a mass-market leisure and entertainment business," Flint said. "And that word, 'business,' brings me to my first major point. We run a business, not a public service. And we run it to be a commercial success. I'm not embarrassed about that."

In shooting for commercial success, should bookmakers be allowed to refuse to take bets from customers who take steps to try to win? On the other hand, should a business be forced to take on a customer they fear will repeatedly damage its bottom line?

The debate is getting ready to play out in state legislatures across the U.S.

In May, the Supreme Court struck down the federal ban on state-sponsored sports betting. Full-scale, legal sportsbooks have since opened in Delaware, Mississippi and New Jersey, and many more states are expected to pass sports betting laws and set up regulations in the coming months and years. International companies are watching closely.

In addition to William Hill, European bookmakers Paddy Power Betfair and bet365 have already entered the U.S. market. Paddy Power Betfair acquired FanDuel, once exclusively a fantasy sports provider, and is now running the sportsbook at the Meadowlands in New Jersey, and bet365 has partnered with the Hard Rock Casino in Atlantic City. Each company has been accused of turning away or severely limiting sharp bettors in the U.K.

One U.K. punter, who had his limits significantly reduced by bet365, provided a transcript of an online chat with a customer service representative who explained that, "We expect this account to be uneconomical based on your type of business."

"When operators get to pick and choose their players based on skill, that goes against integrity and transparency -- the first right of the Sports Bettors' Bill of Rights," said Brian Hess, director of The Sports Fan Coalition, a Washington, D.C.-based group that is lobbying states for a consumer-first approach to sports betting. "Clear, public disclosures of this practice and open competition would encourage fans to only bet where operators are fair and honest."

New Jersey is one of the only states in which gaming operators are not allowed to refuse to take bets from players who are simply using skill, a protocol backed by a 1982 decision from the Supreme Court of New Jersey.

However, in early August, a bettor told ESPN that he was cut off at the William Hill sportsbook at Oceans Resort in Atlantic City, after placing just two bets, the largest of which he lost.

"I had bet $8,400 to win $4,000 on a tennis match and $2,000 on a [first-five-innings] total on baseball," said Shane Sigsbee, founder of Las Vegas-based sports betting group Imawhale LLC. "I went up to bet on the White Sox, and the teller told me that they had to call the Las Vegas headquarters. He returned and told me that because I was banned in Nevada, I was also banned in New Jersey."

New Jersey Division of Gaming Enforcement is actively looking into the overall issue of banning bettors.

"The New Jersey Division of Gaming Enforcement's policy is that patrons cannot be barred from wagering based solely on their winnings or skilled play," David Rebuck, director of gaming enforcement, said in a statement to ESPN. "The New Jersey Supreme Court has previously ruled that patrons cannot be barred from wagering at a facility unless they are on the exclusion list or self-exclusion list or they were caught or suspected of committing any action that may violate the Casino Control Act or State regulations, such as cheating or otherwise being disruptive to operations. These same rules apply to sports wagering.

"However, a facility can take action against skilled players, such as lowering an individual's bet limit. Additionally, online accounts may be closed by an operator for misconduct such as returned funds, bonus abuse, bullying in a chat room, or other terms and conditions violations."

The search for solutions

This debate isn't an issue for the majority of the betting public in the U.S., which isn't a longer-term threat to the bookmakers' bottom lines -- and probably won't ever have to deal with being banned or limited. However, in the U.K., some casual punters, who weren't playing for high stakes, have been impacted.

"That's why we launched Justice for Punters," said Chappell, who started the advocacy group for U.K. bettors in 2015 and now has more than 2,000 followers. "Some of us are professional gamblers, but some of us are just recreational punters who try hard."

Chappell said the practice of restricting or banning U.K. bettors really increased around 2007, after many of the larger corporate bookmakers bought up independent shops and the industry consolidated.

"They were no longer bookmakers," Chappell said. "They became corporations that had to increase their profit every six months. They were no longer run by traders, they were run by investment bankers and accountants, who were going to the older generation asking, 'Why are you letting people win at all?'"

Some jurisdictions are trying to come up with solutions.

In 2016, the racing commission in Victoria, Australia, implemented a minimum bet limit (MBL) on some thoroughbred races. Photo by Michael Dodge/Getty Images

In 2016, the racing commission in Victoria, Australia, implemented a minimum bet limit (MBL) on some thoroughbred races. Licensed operators are required to accept any bet to win up to 2,000 Australian dollars or face penalties. If MBLs were applied in the U.S, bettors could be guaranteed the right to bet $2,200 to win $2,000 on an NFL game or $50 on a 40-1 longshot to win the World Series, for example.

Under the MBL rules, licensed bookmakers in Victoria are prohibited from closing or restricting a betting account that is complying with the established minimum bet limits.

Bookmakers Paddy Power Betfair and William Hill have tried the idea of minimum bet limits in the U.K.

"We are trying to find a balance between catering to recreational customers -- which the whole industry is doing -- and giving customers who want to bet more the opportunity to do so," William Hill UK group trading director Terry Pattinson told gaming industry trade publication EGR in late July.

Minimum bet limits are relatively new and have been restricted to horse racing to this point. Gaming experts say they are one potential solution to tackle the practice of bookmakers avoiding bets from sharp players. But some experts aren't sure professional bettors will like the outcome of forcing books to take their action.

"In a weird way, be careful what you wish for," said Matthew Trenhaile, a London-based veteran of the international sports betting industry. "Because if you force the bookmakers' hands, they will get better at this and they will squeeze the sharps out."

Trenhaile, whose background is in finance and as an odds compiler in between stints working with professional bettors, said a well-run peer-to-peer betting exchange with high-level, reputable financial backing could be a possible solution to the problem in the U.S. In a betting exchange, bettors post and accept or "match" bets offered by other bettors. The platform takes a commission for brokering the transaction, while not facing any of the risk. Betfair and Smarkets, another U.K. company eyeing the U.S. market, are examples of betting exchanges.

"If you got a genuine Wall Street brand investing in some sort of sports betting exchange, like a Citibank, if they had that behind it, it could go really well," said Trenhaile, who also referenced Amazon as another possibility.

Stakeholders, including professional bettors, are paying close attention as legal bookmaking begins to expand across the U.S. They're making their voices heard on social media, expressing their disgust and drawing attention to things like greater-than-normal vigorish being charged by some new bookmakers in addition to the increasing frequency of being prohibited from placing bets. They've heard the rhetoric about how the creation of the legal market will allow them to move out of the unregulated offshore industry, but then ask what they're supposed to do when the new legal books refuse to take their action.

"What I like is that America is very much exhibiting a strong fear of this," Trenhaile added. "And by being very public with their fear, I'm hoping that information filters back to the large bookmakers, because then they can tailor their product."

However, unless forced by states and regulators, it's a long shot that bookmaking corporations suddenly begin making business decisions to cater to the small percentage of their clientele they believe negatively impact profit rather than serving that vast majority of customers who pay the bills.

"Welcome to the wonderful world of having legalized sports betting," said Donoghue, the U.K. gaming consultant. "My view on the U.S. opening up is that it's going to be a major pain in the ass."