Adriene Hill: Las Vegas is expecting its biggest New Year’s ever. More than 300,000 revelers are expected to pour into the city this weekend. It’s big money — especially gambling, which has more and more states looking for their own piece of the action, after a new ruling by the Department of Justice opens the door for online betting.

Marketplace’s Gregory Warner reports.

Gregory Warner: The Federal Wire Act was passed in 1961 to take down the bookies of organized crime. The act made it a crime to send bets over a wire. In the ’90s, the act was expanded to include the Internet.

I. Nelson Rose: This has prevented states from legalizing, like, Internet poker!

Professor I. Nelson Rose specializes in gambling law at Whittier Law School. He says the Department of Justice reversed its stance. Online gambling is OK. Sports betting is still illegal. Each state has to pass its online gaming laws. Only Nevada and D.C. have done so. Iowa and California could be next. Supporters say states could take in millions by taxing online games and selling lottery tickets online.

But there is a danger.

Rose: It does bring gambling into the home. And there is a danger when gambling is too easily available.

The version of the law passed in D.C. has an answer to that. Gamblers have to bring their laptops to one of 20 hotspots around the city. Think of it as a casino — in a Starbucks.

In Philadelphia, I’m Gregory Warner for Marketplace.