In August, 1973, a white man, Mark D. Oliphant, went onto the Suquamish Indian Tribe's reservation in the state of Washington and became involved in an altercation that led to his arrest.

He was charged by the tribe's Provisional Court with assaulting an officer and resisting arrest, held for a while on that court's order' and finally released.

Oliphant promptly filed suit claiming that the tribe had no legal power to try a non-Indian. A federal district court judge said he was wrong. Oliphant appealed. An appeals court said he was wrong, too, and in an opinion that still stands declared:

"Surely the power to preserve order on the reservation, when necessary by punishing those who violate tribal law, is a sine qua non of the sover-eignty that the Suquamish originally possessed."

The decision upholding tribal justice codes against intruders is a little piece of a dramatic phenomenon - the triumph of American Indians in their assertion of a new tribal nationalism.

It has come, during the past five years, through a bewildering assortment of cases, some of them minor. Albert LeBlanc, a Chippewa in Upper Michigan, went fishing without a license, claiming his tribe had been guaranteed unfettered fishing rights in a treaty 140 years ago. He won in the Michigan Supreme Court.

Others are sweeping in their scope.

The Crow Indians in Montana claimed they were being cheated by their leases with big corporations which mine millions of tons of coal on their reservation.Two former Interior secretaries agreed with the young Crow lawyers and overturned the leases.

The victories touch every facet of Indian life. Ancestral fishing rights in Puget Sound were guaranteed by the courts for one tribe. Apaches in Arizona won the right to prevent orphans from being adopted off the reservation without tribal sanction. In six Eastern states, aboriginal land is being claimed by tribes long dormant and the federal government has begun upholding their claims.

It is a reverse of the traditional picture of the hapless American Indian - always pushed around, badgered by white intruders, manipulated by officialdom in the form of the Bureau of Indian Affairs.

Behind it all is the old concept of tribal sovereignty, the agreement, repeatedly abrogated through the years, that Indian tribes were nations which settled their own differences with settlers and were guaranteed control over their own reservations. The re-emergence of tribal nationalism, says Boulder, Colo., lawyer Daniel H. Israel, has occurred "as a direct result of the willingness of American Indian tribes to assert their unique treaty and reservation rights.

"For the first time in over one hundred years, they are acting consistent with their status as domestic sovereign nations."

Not unexpectedly, the new legal militancy has aroused a growing white counter-reaction. Angered by the increasing land claims, tribal law and order codes, and asserted fishing rights, non-Indians from 17 states have formed the Interstate Congress for Equal Rights and Responsibilities.

With a membership swelled in just one year to 10,000, the organization lobbies congressmen and files law-suits challenging the Indian claims. Its origins, in Utah, exemplify the many frictions building around the country.

In September, 1975, Ute Indians promulgated a law and order code there and claimed taxing and police powers for a 3-million-acre swath of land they claimed is historically part of their reservation but which was opened up for homesteading in 1906. About 1,600 whites now living in the disputed territory became angered when Indians arrested one of their own, a deer hunter who strayed through.

"The citizens here feel we've proved up our claims and we own the land and we can't see why it should be the jurisdiction of the Indian tribes," said Hollis Hullinger, mayor of Roosevelt, Utah. "This has been considered whites' territory for 70 years."

Hullinger helped to form the Interstate Congress and is now a vice president. Among its leaders is a selectman from Mashpee, Mass., where the Wampanoags are demanding three-fourths of the land, and Bud Wolfe of Hayward, Wis., who became irate when the Lac Courte Oreilles Reservation, bordering his fishing resort business, was placed under an Indian law and order code.

So far, the Interstate Congress has not been very successful in enlisting support from lawmaking bodies and the general public. "People who don't live close to the reservation don't see the problem," he said.

Tribal leaders give varying explanations for the recent assertions of Indian sovereignty. Some trace it to Robert F. Kennedy's pleadings for Indian rights in the mid-1960s, when his Senate subcommittee explored life on the reservations in the West.

Others see it as a more complex outgrowth of the 1960s, with its civil rights protests by blacks and the futile militancy of Indian radicals who tried armed takeovers. Rather quickly, in latter '60s federal government policy began to change to one of Indian "self-determination." Under that concept, the federal bureaucracy began to take its role as trustee of Indian rights more seriously and began helping Indianassert those rights in court. A crucial landmark, Indians now say, was President Nixon's proposal giving tribes direct control over many federal aid programs channeled into reservations where a half-million Indians lived.

Another explanation is simpler: the Indians got a bunch of good lawyers. Many of them emerged from the old anti-poverty legal assistance programs launched by President Johnson.

By far the most influential is the Native American Rights Fund, based in Boulder, Colo. Heavily financed by large foundations, it has a staff of 20 lawyers and has fought cases ranging from Eastern land claims cases in Maine and Massachusetts to water and fishing cases in the West.

Thomas W. Fredericks, the fund's director, believes the large assemblage of legal talent was the key to asserting the old Indian rights in modern courts. In his view, there was an enormous body of law available to support those claims to sovereignty which no one knew how to use.

He cites the Eastern land claims cases in which two tribes, the Passamaquoddies and the Penobscots, are suing for 12.5 million acres - 58 per cent of the state of Maine - they say was illegally taken from them.

"There wasn't any real question about it once you looked into it," Fredericks said in a recent interview. "The states had negotiated that land away in agreements with the Indians, but the Non-Intercourse Law (a 1790 statute) clearly says that wasn't valid unless Congress assented, which it didn't . The Indians were illegally dispossessed by the states. It was just a matter of someone taking the time and having the legal background to go into it."

There also has been a marked change in the federal government's approach. It is astonishing to many longtime observers of Indian affairs how swiftly the attitude shifted from one of paternalistic manipulation to active promotion of tribal nationalism and self-determination.

"We have come a long way and we've got a start," said Don Miller, director of the Washington office of the Native American Rights Fund. "Compared to what went on before 1970, it's the difference between night and day."

Since 1970, when Nixon made his speech encouraging Indian self-determination, more and more tribes have successfully asserted their right to control the circumstances in which they live. One reason for the success, Miller said, is the wide array of federal aid programs - for education, legal services, health care and housing - that have become available. Those services are provided directly to the tribal governments or other Indian organizations and the tribes no longer are tied exclusively to the Bureau of Indian Affairs, when they seek government services.

At the same time, the government has become more protective of many of the rights enjoyed by tribes under old customs and treaties. There is a growing string of cases in which federal attorneys have backed the Indian claims in court, much to the dismay of affected whites.

Two former Interior Secretaries, Rogers C. B. Morton and Thomas S. Kleppe, supported tribal claims that their interests had not been protected in coal leases on Cheyenne and Crow lands in Montana. Those leases, which had been negotiated under BIA supervision, had opened up billions of tons of coal to corporate strip-mining.

In its role of ultimate trustee, the government has filed suits, or supported Indian suits, in dozens of cases involving Indian land, water, fishing and hunting cases. In a minor example, a U.S. attorney recently sued to expand the fishing and rice-gathering rights of the Red Lake band of Chippewas in Minnesota.In a major case, the Department of Interior has supported virtually all of the land claims lodged by the Penobscots and Passamgquoddies in Maine.