ONCHAN, Isle of Man—It takes an hour by plane and almost three by ferry to reach this island-country smack in the middle of the Irish Sea. Here, on top of a bluff with magnificent views, is a modern building shaped like a Victorian-era hotel that was once on the site.

It is the headquarters for PokerStars, the largest online poker company in the world by a wide margin. And it is from this unusual perch the company is playing a difficult hand: just two years after being shut down in the U.S., and with its founder living here with a warrant out for his arrest, it wants to return to the U.S.

Until a year ago, the U.S. Justice Department considered online gambling illegal, but PokerStars, arguing against that interpretation of the law, kept taking bets until the government filed a civil action against it. Now, the legal landscape has taken a surprising shift, and states like Nevada and New Jersey have passed laws allowing some forms of online gambling. PokerStars, which reached a $731 million settlement with the government but admitted no wrongdoing, wants back in.

"Normally, companies who have founders who are under indictments don't go applying for gambling licenses," said Nelson Rose, a gambling law professor at Whittier Law School, in Costa Mesa, Calif.

To some extent, analysts say, the PokerStars homecoming bid reflects the difficulties many states will face as they open their doors to a long-banned business, itself a groundbreaking development. A good number of PokerStars' online competitors have had their own legal issues, or operate in countries that don't license online casinos. "There aren't pure companies," said Clive Hawkswood, the chief executive of the Remote Gambling Association, a trade group for online gambling.