Will it be a slam dunk for the US sports betting ban?
A ban on sports betting in most US states could be overturned by a case being considered by the Supreme Court.
The state of New Jersey is challenging the 1992 federal law that largely outlawed sports gambling, describing the matter as a "states' rights" issue.
The case, which began on Monday, comes after New Jersey residents voted in 2011 to legalise sports betting.
A group of sports leagues opposes betting on games, which they fear will encourage match-fixing.
Lower courts have consistently ruled against New Jersey, saying it is within the federal government's power to limit a state's policy options.
The Supreme Court opted to hear the case nevertheless amid a wider shift in American attitudes toward gambling.
Before 1976, Nevada - home of the Las Vegas strip - was the only state with legal casinos outside Native American lands.
But in recent years, states hungry for tax revenue in the wake of the financial crash have enacted a rash of looser gambling laws, collecting hefty levies on gambling revenue.
There are now 24 states with commercial casinos - roughly double the number a decade ago.
Despite the official ban, which already exempts Nevada and three other states, illegal sports betting is rife in the US.
Americans place about $154bn in illegal sports bets every year, according to the American Gaming Association.
The association's president, Geoff Freeman, described the federal ban as an "utter failure" earlier this year.
It says the UK is an example of a country where sports betting is commonplace.
"It's time for Washington to stop depriving states of critical tax revenue and allow them to reap the rewards of a regulated market," Mr Freeman said.
More than 15 states filed papers in support of New Jersey in the case. A handful have already passed laws to authorise sports betting in the event of a change.
'Times have changed'
On Monday, as lawyers started arguments for the Supreme Court, some more conservative judges appeared sceptical of the existing law.
The court is expected to make a decision in June 2018.
"If we are successful here we could have bets being taken in New Jersey within two weeks of a decision by the court," said outgoing New Jersey governor Chris Christie after attending the court hearing. "We're prepared in New Jersey - we're ready to go."
Regardless of the court's final ruling, Congress may also take up the debate amid broader discussion about online gaming and e-sports.
Even some of the professional sports leagues have started to change their positions on the question of gambling.
Adam Silver, National Basketball Association commissioner, supported a federal law that would create a uniform set of rules across the US. "Times have changed," he wrote in a 2014 opinion piece.