Regulated sports betting is spreading rapidly around the nation, and the NFL is trying to stay ahead of potential problems with increased monitoring and education, while hoping stiff penalties act as a deterrent. Recent events suggest the enhanced measures are warranted.

In the wake of five players being suspended in April, the NFL is investigating a second wave of potential violations of its gambling policy, multiple sources told ESPN. The uptick in gambling-related issues comes five years after a landmark ruling from the U.S. Supreme Court.

On May 14, 2018, the Supreme Court struck down the Professional and Amateur Sports Protection Act (PASPA), the federal statute that restricted regulated sports betting to primarily Nevada since 1992. The NFL was a plaintiff in the case and had fought to stop the spread of betting for more than two decades, but it pivoted after losing in the Supreme Court.

In the past five years, the NFL has embraced the new landscape, including allowing players to bet on sports other than the NFL.

Thirty-three states, the District of Columbia and Puerto Rico have launched legal betting markets, with regulated sportsbooks in the U.S. handling more than $220 billion in wagers since 2018, according to the American Gaming Association. The NFL has three official sportsbook partners -- Caesars, DraftKings and FanDuel -- and allows sportsbooks to operate at league stadiums. Point spreads and odds that used to be off-limits are now integrated into pregame shows and media coverage, and commercials for sportsbooks are shown frequently during NFL games. With betting menus growing rapidly, there is money on the line on practically every play.

And as opportunities grow, so too does the potential for violations.

Seven NFL players, at least one assistant coach and an undisclosed number of team employees have been found to have violated the league's gambling policy in the past five years. Former Detroit Lions receiver Quintez Cephus, former Lions safety C.J. Moore and former Washington Commanders defensive end Shaka Toney were suspended in April for at least one year for allegedly betting on the NFL. The same penalty was levied against Jacksonville Jaguars receiver Calvin Ridley in 2022, when he was with the Atlanta Falcons, and former Arizona Cardinals defensive back Josh Shaw in 2019.

Also in April, Lions receivers Stanley Berryhill and Jameson Williams were suspended for six games for allegedly placing bets -- not on NFL games -- while at a team facility. And in December, New York Jets receivers coach Miles Austin was suspended by the league for, according to his legal representation, "wagering on table games and non-NFL professional sports."

The April suspensions brought into focus the different ways the NFL is catching those who violate the gambling policy, including third parties in partnership with the league using geolocation to identify bets being placed from prohibited jurisdictions, such as team facilities.

Additionally, companies, including NFL partner U.S. Integrity, are developing platforms aimed at tracking bets placed by prohibited individuals such as players and coaches. Leagues or teams would provide a list of prohibited bettors to the platforms, which would then be shared with sportsbooks. If a prohibited bettor attempts to wager, the technology flags it.

The evolving landscape raises questions about the NFL's relationship with gambling, whether players are properly informed about the league's policy and why the violations are being discovered. Here are some answers based on what we know at the moment.

What is the NFL's policy regarding sports betting, and how does it differ for players, coaches and front-office staff?

NFL personnel, which includes league-office employees, team employees, players, owners, coaches, trainers, officials, security and stadium workers, among others, are prohibited from "placing, soliciting or facilitating any bet, whether directly or through a third party," on any NFL game, practice or other league event, such as the draft or combine.

An exemption allowing players to bet on sports other than the NFL was added to the NFL's gambling policy in 2018 after the PASPA decision, but with a restriction on placing bets from league and team facilities. Before the change, players were prohibited from any sports betting. The change to the policy was part of an agreement between the league and NFLPA and put the NFL's gambling policy in line with other major professional leagues.

How does fantasy fit into this?

The NFL does not consider fantasy sports to be gambling, but it does place restrictions on the type of contests and the value of the prizes available to league personnel, including players. NFL personnel may not accept prizes from any seasonlong fantasy contests in excess of $250. They may not participate in any "daily or other similar short duration fantasy football game that offers a prize."

The 2022 NFL gambling policy states, "These prohibitions are intended to avoid any appearance of impropriety which may result from participation in fantasy football games by an individual perceived to have an unfair advantage due to the preferential access to information."

Why are these violations being discovered now?

Since the Supreme Court ruling, the NFL has embedded itself in the sports betting industry. The league beefed up its in-house technology, dedicating security personnel to the space and partnering with sportsbooks and integrity firms to create a network of sources that monitors the betting market and identifies improper bettors. The league now has more visibility of bets on the NFL, where they're placed and who made them.

Sportsbooks and state regulators use geolocation services to track where bets are placed. After the suspensions in April, the NFLPA sent an email to all agents, alerting them that some of the violations involved players placing bets while using mobile apps on their phones while at work or while traveling with their teams. "This is a violation of the NFL's gambling policy," Ned Ehrlich, the NFLPA's associate general counsel, wrote in the email obtained by ESPN.

"During the NFL's investigations," Ehrlich added, "we have learned that these apps [like FanDuel] are highly sensitive and very sophisticated at tracking, among other things, user location to be sure that people using the app are not 'prohibited gamblers' and/or that the person using the apps is in a location where they are allowed to place bets on the app."

Many state gambling regulations require sportsbooks to obtain the services of an integrity firm. These companies act as a hub to report suspicious wagering, which is then investigated and often communicated to the sports governing bodies. In Ohio, for example, regulations require integrity monitors that receive reports of suspicious wagering to "provide a report to the commission, its contracted sports gaming proprietors, all certified independent integrity monitors and appropriate sports governing bodies." In addition, sources familiar with NFL partnerships in the gambling space say companies are generally obligated to communicate suspicious activity with the league.

"We have long focused on expanding our monitoring efforts, working with a variety of tools and resources while remaining in sync with the growing regulated market," David Highhill, a vice president and general manager who oversees sports betting for the NFL, wrote in an email to ESPN. "Our monitoring efforts include internal measures, along with resources and services provided by our partners to ensure we have the most comprehensive information possible."

How does the NFL educate players, coaches and others about its gambling policy?

The NFL says it educates more than 17,000 people annually, providing training on its gambling policy to all players, coaches and staff employed by all 32 teams, as well as league personnel and stakeholders.

It's not a "one-size-fits-all" process, according to Highhill, who says the education is tailored to the different types of personnel. Most of the training, particularly for players, is held in person, along with online courses and regular reminders throughout the season.

"The education and training the players receive is different than what NFL/club staff receive, which is different than what officials get," Highhill wrote. "We are very explicit in the training to explain that if you are involved with the NFL, you can never bet on the NFL.

"There should be no misunderstanding on the policies," he added.

Why did penalties in April vary?

The penalties varied because there were different violations. Cephus, Moore and Toney received indefinite suspensions of at least one year because they were found to have bet on the NFL. They will be allowed to file for reinstatement in 2024. The precedent for the indefinite suspension of at least one year was set in 2019 with Shaw, who the league determined bet on the NFL while he was on injured reserve for the Cardinals, according to the league. Ridley also received an indefinite suspension of at least one year and was reinstated in March.

Berryhill and Williams received six-game suspensions because they bet on non-NFL events, but according to the league, they did so at a league facility or while traveling with the team.

In what ways is the NFL vulnerable to violations of its gambling policy?

Preventing a player from placing bets on the NFL is extremely difficult. There are many workarounds to avoid detection, such as having an associate place a wager for a player. It's a violation of the gambling policy, but difficult to detect. Players could also bet outside of the regulated betting market in the U.S., with an offshore sportsbook or a local bookmaker who don't have partnerships with the league and are not obligated to alert the NFL of any such activity.

Deterrence might be the biggest weapon the NFL has in combating violations to its gambling policy, but as the recent suspensions show, it's not without limitations.

Has there been evidence of any game manipulation?

The NFL says it found no evidence of game manipulation in any of the suspensions that have occurred in recent years. Highhill says the league analyzes betting information made available by regulators and sportsbook partners to look for signs of manipulation

Signs of manipulation could include unexpected or unusual odds movement or suspicious betting patterns, such as a type of prop bet attracting more wagering than normal.

"We have seen no evidence of game manipulation to date," Highhill wrote.

How does the league reconcile its gambling partnerships and its policy?

In addition to its three official sportsbook partners, the NFL has relationships with international and domestic firms that help monitor the betting market, including Genius Sports, Sportradar and U.S. Integrity. The NFL also maintains open lines of communications with state regulators.

At least two NFL stadiums -- Arizona's State Farm Stadium and Washington's FedEx Field -- will have sportsbooks on premises this season. In March, league owners voted to allow the stadium sportsbooks to remain open on game days, a change in NFL policy. The league also allows up to six sportsbook commercials during game broadcasts.

"Professional sports leagues have largely embraced sports betting as a profitable venture," Jeff Ifrah, a Washington, D.C.-based attorney who advises NFL players on the league's gambling policy, told ESPN. "This is evidenced by the many in-person sportsbooks connected to sports stadiums and the advertising deals between the sports league and sports betting apps. Despite actively encouraging its fan base to bet, the NFL has implemented a zero-tolerance policy for its players.

"There is a distinct lack of nexus between the harm the NFL is trying to prevent and the gambling policy in practice. As a result, most players who engage in sports betting are not doing anything illegal, they are simply not in compliance with a broad company policy governing player behavior."

Highhill says regardless of the NFL's commercial activity in the sports betting space, protecting the integrity of the game is the league's No. 1 priority.

"There is simply no way to have any tolerance when it comes to our players, coaches, or staff betting on NFL football," Highhill wrote. "As individuals involved with the NFL, whether player, personnel, or staff, we have different obligations [and in some cases relevant state laws] than our fans that mean we cannot bet on football. This should not be surprising or controversial."