I hadn't been in the Supreme Court chamber for 10 years, not since that Saturday in June 1971 when I was there listening to oral arguments as one of the 14 Washington Post defendants in the Pentagon Papers case. If it never occurred to me that I might end up in jail, should the Nixon administration prevail, the silent flights of my imagination could not have conjured up the sequence that led from the Pentagon Papers to Watergate, from the Vietnam War to our greatest constitutional crisis since the Civil War.

Four days after those oral arguments the justices ruled, 6 to 3, in favor of The Post and its fellow defendant, The New York Times. That was on June 30, which just happened to be, by prior arrangement, my last day as a full-time journalist. Recently I have been back to the court, the Congress, the White House and some of the executive departments, reflecting on the decade since I retired and thinking about the future.

The first thing that struck me was that the court has been the most stable of our three branches of government. Oh yes, there have been changes. While listening to the justices summarize opinions I was sitting behind two artists who were doing those sketches you see on television, a Burger concession to keep the cameras out. And the furniture has been altered: Instead of sitting behind a straight bench, the nine justices now are arranged, three-three-three, behind a "winged" or half-hexagon bench the better to see and hear each other.

In the decade, Justices Black, Harlan and Douglas have been replaced by Powell, Rehnquist and Stevens. The result has been a considerably more conservative court. But remember that by 1971 the first Nixon appointments already had ended the liberal Warren Court era. And surely forthcoming Reagan appointments, beginning with the replacement for Justice Stewart, will continue this trend. It is profoundly true that a president's most lasting influence often comes from his Supreme Court appointments.

Vagrant thought: If today's most conservative justice, Rehnquist, remains on the bench until he is as old as today's oldest justice (Brennan), he will still be there in 1999. And if he stays as long as Douglas did, he'd be there in 2008!

I'd guess that the present-day court would rule the same way in the Pentagon Papers case because Nixon & Co. went too far in invoking prior restraint against the press. But if such a bald infringement on the first amendment still would not be permitted, the justices in one case after another this past decade have been circumscribing that amendment's reach, especially when it is in conflict with other constitutional guarantees. More of the same is in prospect.

A decade ago Attorney General John Mitchell was excoriating the news media for a "shocking attempt for truth and a cheap surrender to instinct." The other day the president's counselor, Edwin Meese III, drew a comparison between a journalist who publishes information from leaked government documents and a fence who receives stolen property. Top executive branch officials perpetually fail to understand that freedom of the press is a guarantee for the public, not simply for publishers, editors and reporters.

When I first came to town in the fall of 1933 the then "Nine Old Men" were about to declare unconstitutional much of Roosevelt's New Deal. FDR reacted by trying to "pack" the court. That was an attack from the liberal left; today it is the conservative right, dissatisfied with rulings on such issues as abortion, school prayer and school busing. The absolutists, those one-issue frenetics and fanatics, now are overplaying their hands, however, and I think they will fail either to amend the Constitution or to deprive the court of jurisdiction in such areas. Nonetheless, this pressure from the right does have an effect; the court is becoming more conservative and not just because of new justices. There's still truth in that fictitious Irish sage, Mr. Dooley, long ago said, that the court "follows the illiction returns."

As I look around today, however, the court as an institution this past decade has been a rock of stability. The chamber is hushed when the "supremes" are on the bench; the old forms ("God save the United States and this Honorable Court!") still have relevance. The court these 10 years indeed has been changing but the process has been evolutionary, not revolutionary. And the court's movement has been positively glacial compared to what's happened to the Congress and the president in the same period of time.

To enter either Senate or House galleries visitors now must go through airport-style security gates where metal objects set off alarms. Terrorism has escalated worldwide. Capitol police seem more numerous; clearly there are more women among them. And there certainly are many more female journalists in the press galleries.

Probably the biggest change in the congressional furniture has been the House's installation of television cameras. The House has not risked letting in outside cameramen/women/persons who might give taxpayers unseemingly shots of members snoozing or indulging in other uninspiring behavior. Reporters can, and do, cover debates from TV screen in office cubbyholes above and behind the House chamber. The Senate is at least toying with the idea of TV but it also will not risk outside camera operators.

Perhaps equal in importance to TV, the House in 1973 installed electronic voting. Instead of wearisome 45-minute roll calls, members now use plastic cards, similar to those so many of us employ to bank at sidewalk machines, which register their ayes and nays (a wonderful archaic pair of words that fortunately persist). The results are quickly flashed on the chamber wall above the press gallery by means of colored lights that cleverly let both names and numbers show through the fabric wall covering only at voting time.

Changing times: Through most of the last decade the name "Helms" in a headline meant Richard Helms, CIA chief, ambassador to Iran, a controversial figure in a period when the nation was critically examining many of its governments's past actions abroad. Today "Helms" means Sen. Jesse Helms, the ubiquitous right-wing North Carolina Republican. He and some of the new crop of GOP senators are so far right in the party's spectrum that, as public radio's Linda Wertheimer aptly put it, such old-time conservatives as Barry Goldwater and John Tower now are the "new centrists."

Two-thirds of the Supreme Court's nine of 1971 are still on the bench as this session ends, compared to barely one-third of the then members of Congress -- only 30 of 100 senators and 132 of 435 representatives have survived. The captains and the kings of old -- we called them barons and wrote about the way they controlled their fiefdoms -- have largely been booted out or departed voluntarily before the storm hit.

The rules for doing business have undergone major changes: Committee chairmen can be ousted by vote of fellow committee members, even legislative markup sessions are open to press and public. Such changes came in the wave of participatory democracy that swept through legislative bodies at all levels all over the nation, the often angry reaction to governmental secrecy about involvement in Vietnam and Nixon's misconduct and ranging down to hanky-panky over local zoning and sewer permits.

Most important of the congressional changes, aside from the infusion of new and rambunctious members, has been the revamping of the budget process, so much recently in evidence. Created by a 1974 act designed to give Congress equality with the executive branch in the budgeting and spending process, the new procedures have become instruments not only for Reagan budget slashing but also for major alterations of much of the social legislation enacted since World War II.

Reagan's budget man, David Stockman, keeps reminding me of FDR's first budget man. He was Lewis Douglas, about Stockman's age and also plucked from the House by the president. He, too, believed fervently in a balanced budget and at first he successfully took on the most powerful pro-spending group of that era, the veterans' lobby. But when FDR deserted him by turning to deficit financing, Douglas became disillusioned and quit. Stockman's fate, if supply-side economics doesn't do all its boosters claim for it, just might carry this parallel further.

Is Washington a better place than it was a decade ago? Then federal troops had just been called in to help prevent a feared disruption of the government by Vietnam War protestors; on one occasion the Nixon White House was barricaded by a protective wall of buses. Today the paranoia and the posion are gone; the White House once again, in a pleasing fashion, is the city's leading magnet, whether one is an insider or a tourist. The redeveloping Pennsylvania Avenue is becoming worthy of once again being called simply yet grandly "the Avenue." The city has many more exciting, even excellent places to eat.

A decade ago the Kennedy Center was about to open; it has proved a great success, whether or not you agree with the architecture. And the new subway, even though it's sometimes frustrating, is basically an efficient gem. The subway has been largely crime-free, but far too many of our streets remain dangerous, some more so than before. That other Washington of the slums, of jobless men, fatherless families and dope peddlers on the streets, remains both a blight and a blot on democracy; only its locale is slowly moving as the city's rebuilding and refurbishing bumps the inhabitants farther from the current city center.

A decade ago the just elected Del. Walter Fauntroy introduced his first home rule bill; today the city runs the bulk of its own affairs, but, alas, too often not very well or downright terribly. Nonetheless, Washington today is crammed with interesting people of all races, creeds and cultures and fascinating events take place daily in a considerably improved ambiance. It remains true that very few of us ever "go back to Pocatello."

Finally, some impressions of President Reagan: He's more like Eisenhower than anyone since Ike in the sense of being Mr. Nice Guy with a ready smile that makes him hard to dislike and difficult to defeat. But this "communicator" is no language garbler as was Ike; he reads, absorbs and speaks well, is about as precise in public as we can expect a president to be and he carries into politics the actor's marvelous sense of timing. His face, physical bearing and general public demeanor all belie his age; only his hands betray his 70 years. He looks more like a president than any of his three immediate predecessors and he is righting the balance between the legislative and executive branches.

He has that political feel of things that's vital to a successful presidency. He knows how to make it seem that he is subordinating politics to whatever, at the moment, he is touting as the national interest. But how bright he really is is hard to fathom; his grasp of the details of foreign affairs, for example, is shaky.

There is, with Reagan, a dogged consistency. Just a decade ago The Post reported that Gov. Reagan had asked President Nixon for a waiver to federal law so that cuts could be made in welfare and medical benefits for some 2 million Californians. Now he's doing the same thing on a national scale at a moment in public opinion that's propitious.

Yes, he oversimplifies. He sees domestic problems from a Horatio Alger viewpoint and foreign affairs as essentially the enduring struggle between the white hats and the black hats. Still, he has shown he can modify, compromise, even retreat as a successful executive must on occasion do.

Importantly, Reagan strikes me as likely to be a lucky president. He may just get the breaks on the economy, maybe even in foreign affairs. But there are caveats: No one can predict the assassin's bullet or a berserk soldier with a nuclear key or the extent of a terrorist's reach. Nor are those in power in Washington usually very good at foreseeing the influence on government of seemingly extraneous developments: everything from the "me decade" and hedonism to the arrival of silicon chips, genetic engineering, lasers and robot manufacturing. And Washington only dimly sees the impact of the current influx of millions of Hispanic and Asian immigrants.

It remains a truth that presidents are rather well circumscribed in what they can do by the times in which they live. And that will hold true for Ronald Reagan too.