BOOK REVIEW / MEMOIRS : One Addict Stands Tall Against System : SUNDANCE: The Robert Sundance Story, <i> by Robert Sundance, with Marc Gaede</i> . Chaco Press / University of New Mexico Press, distributor. $19.95 cloth, $12.95 paper, 300 pages

On anyone’s scale, a Skid Row wino has to be one of America’s least powerful people. Next time you see one of those ragged figures sprawled on a sidewalk, consider the improbability of what Robert Sundance did in 1975: With an eighth-grade education and nearly 500 arrests on his rap sheet, he sued the city and county of Los Angeles to demand better treatment of street alcoholics by police and the courts. And won.

As a result of the “Sundance Case,” a Los Angeles Superior Court judge in 1978 ordered sweeping changes. Drunks who had been simply thrown in jail were given medical treatment and released much sooner. Arrests for public intoxication in L.A. declined from 50,000 in 1975 to 4,000 a decade later. Weingart Center detox program opened on Skid Row in 1983.

Sundance, who had been jailed an average of 226 days a year for the 14 years preceding his lawsuit, sought to have arrests of street drunks declared unconstitutional. He directed the Indian Alcoholism Commission of California, a lobbying and educational group, from a Skid Row hotel room.

Although Sundance died last year without achieving his ultimate goal--the state Supreme Court rejected his petition in 1987--he had improved the lot of his people and, as novelist Thomas McGuane writes in the introduction, “owned his own life.”

How did he do it? In this memoir, which he began dictating to Marc Gaede in 1990, Sundance describes his harrowing odyssey through bars, whorehouses, alleys and jails all over the West. He gives some clues to his redemption but, in the end, remains an enigma.

Born Rupert Sibley McLaughlin on the Standing Rock Sioux Reservation in Wakpala, S.D., in 1927, he was initiated into a demoralized, poverty-stricken culture in which alcohol, although forbidden by law, was the only balm. “Drinking became a status symbol among Indians,” he writes. “Kids saw drinking as the main way to grow up.”

At 15, he lied about his age and joined the Navy so he could leave the reservation and buy booze legally. He was an antiaircraft gunner on the carrier Ticonderoga during World War II. Then he resumed what was to be, despite stints as a rodeo rider, ranch hand, construction worker and firefighter, his only real career: drinking.

Sundance pulls no punches. He tells of the wino’s life--its casual violence, its ceaseless wandering, the terrors of delirium tremens--in blunt, convincing terms. The only problem is that in reliving his years on the bottle--the wild highs as well as the lows--he sometimes slips back into attitudes that he claims to have outgrown.

“After I quit drinking . . . I understood the seriousness of rape,” he assures us after a series of would-be comic anecdotes about unconscious women being gang-raped on barroom floors. “But I didn’t know it was rape back then. I thought the broads were just playing hard to get.”

In Los Angeles, something happened. McLaughlin rediscovered his roots, taking the name Sundance in 1970. And he concluded that the same system that conspired to keep Native Americans drunk and dependent was using street alcoholics as slave labor.

Sundance began his lonely crusade, sending 80 petitions to judges before he got an encouraging answer and help from public interest lawyers. After he filed the suit, he writes, Los Angeles police tried to kill him. He persevered.

Here we confront the enigma of Sundance. With disconcerting ease, he blames his years of petty and not-so-petty crime on alcohol, and blames alcohol on the white man--yet a more guilt-ridden person probably would have remained mired in booze.

Like many victims, he sees “the system” as more consciously malevolent than it is--yet this gave him motivation to fight it. No saint, he showed that even an ordinary person can enlist his flaws in the service of an astonishing empowerment.