IN MAY 1978, when Soviet human-rights leader Yuri Orlov was put on trial for crimes against the state, Moscow's lilacs burst into bloom.

Orlov had called his unofficial group the Helsinki Monitoring Committee, because the Helsinki Accords signed by the Soviet Union in 1975 included guarantees of international civil liberties. Soviet leader Leonid Brezhnev was infuriated. He had signed the accords solely because they also guaranteed the inviolability of Europe's post-World War II frontiers -- in effect, a guarantee of Soviet totalitarian hegemony over Eastern Europe.

Orlov got the max: seven years' hard labor, five years' internal exile. As we Western reporters waited outside the courthouse for the pre-ordained guilty verdict, the lilacs nearby drenched us in intoxicating, utterly incongruous fragrance.

The phony legal proceeding opened an era of harsh human-rights repressions across the Soviet bloc. Hundreds of activists, inspired like Orlov by the Helsinki agreements, were jailed or exiled. The United States, a co-signer of the accords with the Soviet Union and 33 other nations, denounced the reprisals to little effect.

But 12 years later, the empire Moscow built on police power and anti-democratic propaganda is no more. Human rights are ascendant in countries where barely a year ago, the secret police reigned supreme.

Now Eastern Europe's future is clouded by economic upheaval and by the need to rebuild basic institutions of government and establish societies on enduring principles of civil liberties. Ethnic and nationalist conflicts threaten this agenda. But the traditions of the Helsinki agreements may have become so deeply ingrained that transgressions against human rights could be interpreted -- and judged -- against the standards established by the accords.

This unexpected outcome is washed in irony. The Helsinki agreement, of no binding legal status among its signatories, was once spurned by conservatives in the United States as another capitulation to communism. Fifteen years ago, opposition to President Ford's signing the accords ranged from newly-exiled Soviet author Alexander Solzhenitsyn to the late senator Henry M. (Scoop) Jackson of Washington to then-governor Ronald Reagan of California, who declared, "I am against it and I think all Americans should be against it."

Moscow, whose domain the accords ultimately helped unravel, first proposed the basic framework in 1968, the year Soviet tanks crushed Czechoslovakia's reforms. By the time the first Conference on Security and Cooperation in Europe got underway in 1973, the auguries for success were poor. Difficulties ranged from too many participants (everyone from the superpowers to the Vatican to the thumbnail principalities of Liechtenstein and Monaco was there) to too ambitious an agenda. Topics for discussion would include everything from military forces, to frontier security, intellectual and cultural exchanges, to civil liberties (the last at Western insistence). The setting seemed perfectly appropriate to the expected outcome: a modest capital on the periphery of Europe, far from the Berlin Wall, the Fulda Gap and other East-West flash points.

Two years later, the conferees produced what they called the Final Act, the Helsinki Accords. World leaders gathered to sign the documents on Aug. 1, 1975.

Gerald Ford, in office less than a year, came largely because he seemed unable to escape it. Before heading to Helsinki, Ford took pains to point out that "the document I will sign is neither a treaty nor is it legally binding on any participating state . . . ."

Brezhnev was at the height of his authority after 11 years in power. The destruction of the Prague Spring well behind them, the Soviets were using Cuba and other willing surrogates to support Marxist insurgents in "wars of national liberation" in Angola, Ethiopia and elsewhere in the Third World. The accords encompassed four so-called "baskets" -- understandings on European security; cooperation on scientific, technical and environmental issues; human rights and cultural cooperation; and future follow-up sessions to determine how well the accords were being fulfilled.

Brezhnev made clear what he thought of Basket Three's human-rights guarantees: "It is only the people of each given state, and no one else, that has the sovereign right to resolve its internal affairs and establish its internal laws."

But the Basket Three provisions, pledging the signing nations to uphold the "universal significance of human rights and fundamental freedoms," powered the most sustained, audacious and eventually successful human-rights drive in modern history. With an audacity that at first stunned, then enraged, the authoritarian countries, hundreds of citizens in the Soviet Union and the bloc countries formed "monitoring groups" to bear witness to their governments' repressions of fundamental human rights. Western media tracked and reported the subsequent reprisals against the monitoring groups.

The seemingly endless flow of this news, augmented by private support groups such as the U.S. Helsinki Watch Committee, made clear to millions in the West the cynicism with which the bloc had signed the accords. The same reports flowed back into Eastern Europe via Western broadcast organizations. Millions there listened.

Unique to post-war East Europe, many of the Helsinki groups cut across class and social lines. Intellectuals, religious activists, nationalists, workers, unionists, tradesmen, invalids -- all had their own denials of rights to report and in country after country, the Helsinki monitors included them in the effort to record humanitarian abuses. Solidarity between workers and intellectuals transformed the nature of the contest between activists and the authoritarian regimes, giving the dissenters an ideological breadth and mass resilience that ultimately withstood subsequent authoritarian reprisals.

Helsinki follow-up conferences -- Belgrade, Madrid, Vienna -- were dominated by criticism of Soviet-led abuses of civil liberties. The Soviets and the other bloc governments in turn denounced the critics and accused the West of systematic abuses. But the tide was flowing against the regimes. Even though the Helsinki groups had been largely driven out of existence or deep underground by the mid-1980s, the political ferment which they helped spark and support was growing into an irresistible force. By the time Mikhail Gorbachev came to power in Moscow in March 1985, the roots of transformation had taken hold, unseen by the West, but certainly clear to Gorbachev. Eighteen months later, the late Andrei Sakharov was freed from internal exile, and Soviet prisons were being forced to yield up Helsinki monitors. Yuri Orlov emigrated to United States.

In a speech to the United Nations in December 1988, Gorbachev declared what the Helsinki agreements had made manifest: "Today, the preservation of any kind of 'closed' society is hardly possible . . . . The principle of freedom of choice is mandatory . . . a universal principle that should allow for no exceptions." The Helsinki Accords' Basket Three provisions deserve a place in history as a landmark of international relations, a kind of International Bill of Rights that has given force and meaning to all other such documents, including the United Nations Declaration on Human Rights. Last week's CSCE summit in Paris went far beyond anything anyone could have predicted for the Helsinki process in 1978: the formal end of the Cold War. The meetings in the Elysee Palace seemed to suggest the eclipse of George Orwell's baleful postwar vision of civil society permanently debased by propaganda and police power.

But the ascendance of democratic governments based on market economics and guided by adherence to fundamental human rights offers complex new problems for Europe. These may be no less difficult or quick to resolve than the political-military confrontation between East and West, which took 40 years and drained the treasuries of two dozen countries. When they take root across the societies of the old East bloc, Western concepts of such things as economic opportunity -- as opposed to the now-meaningless Marxist guarantee of a job -- seem certain to trigger major east-to-west population moves as impoverished Easterners try to invoke a right to live where they please. When free-market forces shut down more and more of the East's antiquated industrial base, the exodus could become a frenzy.

Gorbachev, on a state visit to Spain last month, looked at the uncertain future and described it with perfect accuracy: "Many interpret this as the beginning of chaos, as irreparable catastrophe. Nonetheless, it is essentially the birth of an entirely new organism."

Not surprisingly, the Paris summit's final full day of discussions was dominated by the economic issue: Hungarian Prime Minister Jozsef Antall warned against a new "welfare wall" between East and West; German Chancellor Helmut Kohl talked about the dangers of a "prosperity divide."

Other humanitarian issues are growing their own new teeth: religious activism, nationalism, ethnicity, property rights, ancestral land claims -- each has an apocalyptic underside that threatens trouble in the future.

But for just this moment, it is worth savoring the unexpected past. The lilacs blooming at Yuri Orlov's trial, it seems, were not incongruous after all -- we just couldn't comprehend what they meant at tbe time.

Kevin Klose, an Outlook editor, was The Washington Post's Moscow bureau chief from 1977 to 1981.