By Tim Dahlberg, AP

There’s a brand new sports bar at Monmouth Park with televisions hanging from nearly every available rafter.

Mostly empty now except on racing weekends at the horse track little more than an hour from Manhattan, it may not stay empty long. Depending on how a judge rules, it could soon become the first fully functioning — and fully legal — sports book in the country outside of Nevada.

The William Hill Race and Sports Bar would become the William Hill Race and Sports Book. And that could be a game changer for anyone in New Jersey who likes to have a little action on their favorite team.

“We’re built out and ready to go,” said Joe Asher, who heads operations for betting giant William Hill U.S. “This is a very sizeable market.”

Of that, there is little doubt. There’s no shortage of sports fans in the New Jersey/New York area, and bookmakers believe they will line up from opening day on with fistfuls of cash to wager on games.

Asher says that if sports betting is allowed in New Jersey it could dwarf the $3.6 billion that was wagered legally on sports last year in Nevada, opening up an entire new industry on the East Coast. It might even help rescue Atlantic City casinos that are struggling to attract customers in the wake of casino expansion around the country.

New Jersey residents want it, voting overwhelmingly in 2011 to permit sports betting at race tracks and casinos. Gov. Chris Christie signed a bill into law approving sports betting, only to see it derailed in court because it conflicts with federal law.

But now the issue is back before a federal judge, and all bets are off. An end-run around the federal prohibition of sports betting in all but four states is once again in play.

And the sharp guys from Vegas are poised, ready to jump in when they get the word.

“I believe the New Jersey market once fully up and going would be at least three times the Nevada market,” Asher said. “This is an area with some of the most storied franchises in American sports where billions of dollars are already bet on sports illegally.”

Unfortunately for would-be bettors, not everyone is enamored with the idea of sports betting. They’re stuck in the past, still believing that betting on sports draws undesirables and is somehow a threat to the integrity of the games themselves. They don’t understand that it’s a lot easier to monitor betting trends in legal books than with an illegal bookmaker operating out of a corner bar.

There are some signs that even that may be changing. Daily fantasy sports wagering is exploding online thanks to a loophole in the federal law, and looks very similar to sports betting.

The NFL, meanwhile, holds games every year in London where there are betting parlors on every block offering a line on the action. And last month NBA Commissioner Adam Silver said at a business conference that he was not opposed to the idea of sports betting and expected his league to participate in it at some point

“Obviously we read with great interest Commissioner Silver’s comments,” said Asher, whose company runs more than 100 locations in Nevada and 2,400 shops in the United Kingdom. “I hope that signals a re-evaluation of what is obviously a mindset that does not comport with 21st Century reality.”

For now, though, the NBA and the other major sports leagues are lining up against betting in New Jersey. Lawyers for the four leagues and the NCAA will argue Oct. 31 before U.S. District Judge Michael Shipp that the injunction he issued last year upholding the ban should stay in place despite Christie’s announcement that the state would not be involved in regulating the betting.

Should the door open in New Jersey, though, other states will surely follow, much the way they did when Atlantic City became the first place outside of Las Vegas to legalize casino gambling. The online market could explode, much like it is in Nevada where 36 percent of William Hill’s handle comes through bets on its mobile app.

Right now all they’re selling at the sports bar at Monmouth are food and drinks. Betting is limited to the expected finishing position of the horses on the track.

It might not be long, though, before you can order an NFL three-teamer to go with that trifecta on the ponies.