A LITTLE-NOTICED law Congress passed in 1988 may bring casino gaming to states that neither want it nor are prepared to deal with its consequences. And Connecticut has no choice but to help lead the way.The Mashantucket Pequot tribe in Ledyard, Conn., is building a multimillion dollar casino on its reservation, several miles from Mystic. The tribe intends to add casino gambling to the already hugely successful high-stakes bingo it runs. The casino, to be completed this winter, will generate a total of $80 million a year in gross revenues, with 5,000 customers a day, according to the tribe. Connecticut doesn't want casino gambling, but has no say in the matter. Congress passed a law called the Indian Gaming Regulatory Act three years ago to regulate the types of gambling operations Indian tribes could run. Under the law, tribes may establish on their reservations only gaming already allowed in the states in which they reside. Sponsors of the law assumed that only in states like Nevada, which already has casinos, would casinos be allowed to open on tribal land. In a 1987 Senate hearing on the matter, Ross Swimmer, assistant secretary for Indian Affairs, specifically asked Congress to make certain that states which allowed charitable Las Vegas nights wouldn't be forced to let casinos open up on reservations. Sen. Daniel Inouye (D) of Hawaii replied, "I can assure you that is my intent as author of the measure." The courts saw the matter differently. Connecticut, like scores of other states, allows charities to raise money by holding occasional Las Vegas nights. It is hardly big business: Less than $100,000 is raised in this manner in Connecticut every year. But the 263-member Mashantucket Pequot tribe seized upon that precedent to mount a legal challenge to gain the right to build a casino on its 2,000-acre reservation. To the surprise of Gov. Lowell Weicker, who didn't oppose the gaming bill in Congress but opposed the presence of casino gambling i n the state, the courts sided with the tribe. A last-ditch effort to outlaw Las Vegas nights failed to pass the state legislature. Reno here we come.The implications for other states are obvious. There are currently 314 tribes on 278 federal reservations in 34 states. Any tribe could fight for the right to build and run a casino, and unless state law expressly forbids casino gambling under any circumstances, the tribe would have a good chance of winning. So states which never intended to have such gambling will be face to face with it as a result, not of the will of Congress, but the whims of the courts. Already, casino gambling is spreading. Tribes in California, Nevada, Nebraska, South Dakota, Washington, and New York are seeking permission to open casinos, according to the Interior Department. A dozen tribes in Wisconsin are suing the state for the same right. A few state governments, which cannot tax tribal revenues, are leaning toward casino gambling themselves. Riverboat gambling is underway along the Mississippi River in Iowa. Illinois and Mississippi plan to follow suit. GAMBLING hardly seems worthwhile when measured against the ills it brings. Each casino in Atlantic City, N.J., is the setting for around 1,000 crimes every year, according to the Atlantic City police department. In rural Ledyard, many residents are fearful of a big increase in drunk driving on the town's winding, country roads. Still, not everyone opposed the Ledyard casino. The local Chamber of Commerce fought hard on behalf of the Indians' cause. The president of the chamber, Dan Danielson, said he lobbied for the tribe because the casino would add 2,000 new jobs to the region. And in an area that is going to see unemployment soar in the next few years due to defense cuts, any new influx of jobs is mighty tempting. The Indian Gaming Regulatory Act may have only hastened the inevitable. More and more, our society seems willing to put more faith in a roll of the dice than an honest day's work. No state lotteries existed until New Hampshire began one in 1964. Just 20 years later, in 1984, there were only 17 lotteries. That number has more than doubled in the last seven years. The United States now has 34 state lotteries, plus one in the District of Columbia. Nationwide, state-sponsored gambling brings in a total of $20 billion a year. Connecticut officials thus appeared hypocritical howling over the Mashantucket Pequot's intentions; the state has a number of different lotteries, off-track betting parlors, dog racing, and jai alai. But at least the revenues all go into the state treasury. The Mashantucket Pequots can laugh all the way to the bank with their profits; not a dime need go either to the federal or state government because tribes are considered sovereign nations. Connecticut and other states have little control over what Indians do with regard to this issue. And that, as much as anything, is driving lawmakers nuts. For 300 years, whites have exploited the Indians. It is poetic justice, perhaps, that the Indians now stand to become rich exploiting the weakness of a predominantly white society. The tribes have learned their lessons well.