For more than a year, Cynthia H. Haines of Marin County, Calif., made a habit of logging on to the Internet to gamble.
She played blackjack, craps, and other games on 50 Web sites, covering her losses with loans from her dozen credit cards. Now Ms. Haines wants the card companies to expunge her $70,000 in gambling debts.
Her argument, laid out in a lawsuit filed Aug. 11 in Marin County Superior Court, is that because Internet gambling is illegal in California, the companies acted wrongly in letting her use her credit cards.
"Ms. Haines will agree that she made a mistake, but legally she doesn't feel she bears any responsibility," said her lawyer, Ira P. Rothken of Corte Madera, Calif.
Ms. Haines' suit-naming MasterCard International, Visa International, Visa U.S.A., and Providian National Bank as defendants-may help determine the future of Internet gambling, which is operated largely by Caribbean offshore companies.
Legal experts say U.S. citizens wager more than $600 million a year on on-line games of chance, and the banking industry may be dogged by more problems as this form of gambling proliferates.
Though Ms. Haines' lawsuit lacks class-action status, she is seeking to prevent card companies from collecting on-line gambling debts from anyone in California.
On Capitol Hill, several federal bills are circulating that would regulate Internet gambling or make it illegal in the United States. Meanwhile, the card companies continue to review their options.
"It's a brand-new industry for us all," said Rob Robbins, Visa U.S.A. executive vice president for merchant acceptance. "Basically we're trying to stay up with it."
Visa, MasterCard, and Providian declined to comment directly on Ms. Haines' case but said it is up to customers to use credit responsibly.
Mr. Robbins said Visa continually investigates chargebacks and other issues that might arise in a shadily run business. Considering how many merchants accept Visa, there are relatively few problems, he said.
"We believe that our payment card should be accepted at any legally operated business," Mr. Robbins said.
Ms. Haines sued Providian because it was the first to sue her to collect a portion of the $70,000. She has indicated she may sue other creditor banks.
"We are looking at (Internet gambling) to see if there's something that we can do," said Laurie Cole, a Providian Financial Corp. spokeswoman in San Francisco. "We're doing that because we don't believe using borrowed money is a responsible use of credit."
Business lawyers have little sympathy for Ms. Haines, who is also seeking unspecified damages from the card associations.
"She gambled and she lost big, and now she is trying to get out of paying," said Philip S. Corwin, a partner in Federal Legislative Associates, Washington. "It's not the duty of the card companies to police the millions of cardholders who are foolish enough to gamble on the Internet."
Leonard T. Nuara, a Morristown, N.J., lawyer who specializes in Internet law, said, "I don't see why the bank should be responsible for the legality of the payment."
It would "set a terrible precedent in the banking industry if people could say, 'Oh, I can void this debt,'" said Mr. Nuara, a member of the American Bar Association's cyberlaw committee.
Mr. Nuara and Mr. Corwin said courts are unlikely to erase Ms. Haines' debts or hold the card companies responsible for merchant practices.
Ms. Haines' lawyer, Mr. Rothken, contended that the card companies have some duty to check on their merchants. He said he notified the defendants in March about the practices of offshore casinos. He also said a simple Internet search turns up dozens of casinos that display MasterCard and Visa logos. Some try to attract U.S. citizens through magazine advertisements and other means.
Mr. Rothken raised the question of "whether or not Visa and MasterCard are aiding and abetting an illegal act."
Among the 50 on-line establishments named in Ms. Haines' suit are Cyber Thrill Casino, which posts its rules in tiny type; InterCasino, which limits a patron's bets to $1,000 a week; and Island Casino, which states on its Web site that customer winnings are not reported to any government agency. At Island Casino, wagers of more than $2,500 on sports events are said to be "subject to approval by management."
The convenience and anonymity of the Internet can prove irresistible to people with compulsive betting problems, according to a member of Gamblers Anonymous.
"I can tell you I'm really glad they didn't have this when I was gambling," said Karen H., a member of the support group. In a telephone interview, she said that she used to find excuses to travel to gambling centers and that Internet gambling would have been a significant temptation.
Edward J. Looney, executive director of the nonprofit Council on Compulsive Gambling of New Jersey, Trenton, said his organization recently got a call from a distraught mother from Pennsylvania whose 20-year-old son tacked $18,000 on the family credit cards at on-line gambling sites.
Moral and emotional issues aside, the legal matters could be complex, lawyers said. Mr. Nuara said the toughest question may concern jurisdiction over offshore gaming: Does a law apply where the computer server is located, or where a cardholder clicked to authorize payment?
Regardless, Mr. Nuara said, consumers would not be excused from their contractual obligations to pay credit card bills.