The United States Supreme Court has overturned a federal law that effectively banned betting on sporting contests in every state apart from Nevada, paving the way for the other states to legalise sports gambling.
The nine judges on America's highest court voted by a margin of seven to two - although one of the seven did so with caveats - to scrap the 1992 Professional and Amateur Sports Protection Act.
The case was brought by the state of New Jersey, which has been trying to break the monopoly enjoyed by Nevada's Las Vegas for years, but it has already been celebrated by the gambling industry.
While sports-based lotteries are legal in Delaware, Montana and Oregon, until now US gamblers could only place bets on individual contests in Nevada, although that did not stop an illegal industry that is estimated to be worth more than £100billion a year.
With significant tax revenues on offer, New Jersey and four other states have already passed bills to legalise sports gambling and 14 more have started the process. That number is expected to double within five years.
The court explained its ruling over 49 pages that can be boiled down to a single argument: the federal government had overreached itself by telling the states they could not do something without actually making it illegal itself.
"Congress can regulate sports gambling directly, but if it elects not to do so, each state is free to act on its own," the court wrote.
Reaction to the decision from the major sports leagues and their player associations, which all opposed New Jersey's attempt to overturn the status quo, has been mixed.
For many in US sport, the opposition was not based on a fundamental revulsion towards gambling - although that does exist - but more to do with concerns about a chaotic roll-out of legal betting and a piecemeal approach to regulating it.
The National Basketball Association (NBA), for example, has previously acknowledged it was probably time to legalise something that millions of Americans were doing anyway.
In a statement, NBA commissioner Adam Silver said: "We remain in favour of a federal framework that would provide a uniform approach to sports gambling in states that choose to permit it, but we will remain active in ongoing discussions with state legislatures."
This stance was broadly in line with the statements issued by the National Collegiate Athletic Association (NCAA), the organisation that regulates America's huge college sports industry, and the National Football League Players' Association (NFLPA).
The NBA, NCAA and NFLPA statements also talked about defending their players' safety and their games' integrity.
These issues are perhaps most acutely felt by baseball, though, as it is arguably the sport that has shaped US policy on gambling for a century.
America's eyes were opened to the risks of match-fixing when the Chicago White Sox - or Black Sox as they became known - were accused of throwing the 1919 World Series, while Major League great Pete Rose remains "permanently ineligible" from the game and the sport's hall of fame for betting against teams he played for and managed throughout his long career.
In a statement on its Twitter feed, Major League Baseball said the decision "will have profound effects" and it will "continue to seek proper protections" for baseball in partnership with the other professional sports.
The Major League Baseball Players' Association executive director Tony Clark went even further, saying the decision is "monumental, with far-reaching implications for baseball players and the game we love".
Clark added: "From complex intellectual property questions to the most basic issues of player safety, the realities of widespread sports betting must be addressed urgently and thoughtfully to avoid putting our sport's integrity at risk as states proceed with legalisation."