When Julius and Ethel Rosenberg were facing death in the electric chair in the early 1950s for passing atomic secrets to the Soviet Union, their sentence was the subject of repeated petitions to the Supreme Court.

At least one of the clerks there had no doubt that the penalty was correct.

"In my opinion," the clerk, William H. Rehnquist, wrote his boss, Supreme Court Justice Robert H. Jackson, "if they are going to have a death sentence for any crime, the acts of these ptrs petitioners in giving A-bomb secrets to Russia years before it would otherwise have had them are fitting candidates for that punishment. It is too bad that drawing and quartering has been abolished."

The observation is contained along with many others in the late Justice Jackson's papers at the Library of Congress. With the permission of Jackson's heirs, the documents were examined by The Washington Post.

A Supreme Court justice since 1972, Rehnquist was nominated by President Reagan last month to be the next chief justice of the United States. The memos he wrote as a Supreme Court clerk reveal that at a time when Ronald Reagan was still a Democrat, Bill Rehnquist was Bill Rehnquist.

They show Rehnquist to be an extraordinarily consistent conservative, a man of the right whose thinking has changed little in more than 30 years. He was a law-and-order man before it was widely perceived as an issue. He was bemoaning the "ivory-tower jurisprudence" of the court well before Earl Warren got there. He was even complaining of the weakening of "local law enforcement" in an era when third-degree methods and coerced confessions had not been ruled unconstitutional by the court.

In his 14 years, Rehnquist has earned a reputation as an outspoken conservative who generally sides with government authority over individual liberties, who is determined to stick to the "original intent" of the framers of the Constitution, and who has a distaste for any judicial expansion of it to deal with contemporary problems.

Those same views stand out clearly in the memos that Rehnquist wrote in 1952 and 1953 when he was one of Jackson's clerks after graduating from Stanford Law at the top of his class.

Rehnquist obtained the prized clerkship with Jackson as the result of a summertime meeting with the justice in the offices of Phil Neal, then a professor at Stanford Law and a former Jackson clerk himself. Jackson often visited the West Coast, particularly to attend the meetings of San Francisco's all-male Bohemian Club that were held each summer on the banks of the Russian River. In August 1951, he stopped by Neal's office for a visit.

Jackson, a 1941 appointee of President Franklin D. Roosevelt who grew more conservative in his later years, and Rehnquist, a World War II veteran who was to graduate that winter, hit it off well. By fall, law firms in California, New Mexico and Arizona had offered Rehnquist jobs, but he had his eyes on the court. He wrote Jackson to ask if the justice might make his mind up sooner rather than later.

Jackson offered him the job Dec. 4, 1951. "I felt at our talk at Stanford that you and I would get along pretty well together," Jackson wrote, "and, if we can make proper arrangements, I will be glad to take you on."

After some mixed signals over when he would take his bar exams, Rehnquist began his 18-month stint in January 1952, plunging into the work of doing research for the justice's opinions and writing "cert memos" -- summaries of cases for which "certiorari" or Supreme Court review was being sought.

Rehnquist's fellow clerk for much of this period was Donald Cronson, later an international lawyer, who, the Jackson papers suggest, was the in-house liberal while Rehnquist was the resident conservative. Each stated his own views plainly and bluntly. Jackson seems to have welcomed the philosophical debate. 'Separate but Equal' Issue

During the 1971 Senate debate over Rehnquist's confirmation, one of his memos, "A Random Thought on the Segregation Cases," became an issue because of its outspoken support of the old "separate but equal" doctrine. Rehnquist blunted the criticism with a letter to Senate Judiciary Committee Chairman James O. Eastland (D-Miss.). Rehnquist said his best recollection was that the memo was prepared at Jackson's request for a conference with the other justices and that it reflected Jackson's views, not his own.

Rehnquist concluded the letter by stating that while Jackson "did expect his clerks to make recommendations based on their memoranda as to whether certiorari should be granted or denied, he very definitely did not either expect or welcome the incorporation by a clerk of his own philosophical view of how a case should be decided."

Efforts to reach Rehnquist for comment Friday were unsuccessful, but the Jackson papers appear to contradict this. Both Rehnquist and Cronson frequently expressed their own views of a case, without any sign of disapproval from Jackson. Rehnquist's memos, in particular, are full of personal observations and philosophical suggestions as to how a case should be decided.

In 1952, for instance, before the court convened for its new term in October, Cronson sent Jackson a memo concerning the plight of a man who had been imprisoned on Ellis Island for nearly two years without a hearing.

The man, Ignatz Mezei, had lived in the United States for 25 years, but he had gone to Europe to try to visit his dying mother in Romania and was seeking to return to his family in Buffalo when immigration authorities stopped him. The government had classified him as a security risk, but refused to disclose its reasons. It took the position that, as an excludable alien, Mezei had "no rights" and that he could be held in executive custody indefinitely.

Cronson warned of what he regarded as ominous implications of the case. He protested that if the government's position were upheld, it would amount to a modern-day version of the "lettre de cachet" whereby the French monarchy imprisoned people without a trial.

Rehnquist countered with a memo to Jackson that began by saying he was submitting "these reflections . . . in great deference, seeing they are contrary to the views of my coworker Cronson , and also to some of the views which you expressed" in an earlier case involving immigration law.

Seventeen other countries had refused to take Mezei after he was deemed unacceptable here, but Rehnquist saw nothing illegal or even lamentable in the plight of the man facing life on Ellis Island.

" . . . (W)hen we come to this guy, who seeks entry under the provisions of the general immigration law, I have some trouble crying," Rehnquist wrote. "I think Congress . . . has provided that this man was properly excludible sic . That it had the power to do so I have not the slightest doubt . . . . If Congress plainly said that all aliens with green hair shall be excluded, I know of nothing in the Constitution which would prevent them . . . .

"This alien is detained on Ellis Island by the government simply because he is unable to go to any other country," Rehnquist concluded. "He is perfectly free to get on the first outbound boat that comes along . . . . I think the government is right."

The court, in a 5-to-4 decision, held that Mezei could be detained indefinitely -- but there was a blistering dissent from Jackson. Evidently unimpressed by Rehnquist's views, he derided the government's assessment of Mezei, a 56-year-old cabinetmaker, as a grave security risk, "a Hercules who might pull down the pillars of our temple." Mezei, the justice said, "must have been astonished to find himself suddenly putting the government of the United States in such fear that it was afraid to tell him why it was afraid of him."

Moreover, Jackson, who had been chief counsel for the United States at the Nuremberg trials after World War II, said the government's legal arguments reminded him of Nazi Germany.

"Quite unconsciously, I am sure, the government's theory of 'safekeeping' without disclosure to the victim of charges, evidence, informers or reasons, even in an administrative proceeding, has unmistakable overtones of the 'protective custody' of the Nazis more than of any detaining procedure known to the common law," Jackson wrote.

Mezei, who had been temporarily free on bond, was sent back to Ellis Island following the March 16, 1953, ruling, but the Justice Department paroled him in August 1954.

There is no indication that Jackson was displeased with Rehnquist for presenting his opinions -- and no indication that the clerk was dissuaded from serving them up.

In a memo commenting on three lawsuits by baseball players against the major leagues for alleged violations of the Sherman Act, Rehnquist made plain that he thought the sport should be exempt from the antitrust laws. "Before making any recommendation," he wrote Jackson, "I feel it is only fair to lay bare my strong personal animus in these cases . . . . I feel instinctively that baseball, like other sports, is sui generis, and not suitably regulated either by a bunch of lawyers in the Justice Department or by a bunch of shyster lawyers stirring up triple damage suits."

A case involving federal lobbying law, U.S. v. Harriss, elicited another tart observation from Rehnquist. U.S. District Court Judge Alexander Holtzoff had held the law unconstitutional, partly on grounds that the penalty, prohibiting convicted offenders from lobbying for three years, violated the First Amendment.

"It strikes me that Judge Holtzoff's holding on the penalty provision is just so much hogwash," Rehnquist asserted. "The government can put men in jail when they are convicted of a crime -- a result which the Constitution would surely forbid if they had not been so convicted. I see no reason why by the same token they may not impair a man's right to free speech, if such impairment be shown to be reasonably related to an offense he has committed and been convicted for . . . . If the government can take away a man's normal right to freedom of movement upon conviction, I cannot believe that his right to freedom of speech is any more precious."

That view seemed reflected this month when the court, in a 5-to-4 ruling, upheld a prohibition on casino gambling ads in Puerto Rico. Writing for the majority, Rehnquist said that if a legislature could regulate a product or activity, then it could regulate the advertising of it. Dissenters contended that a ban on truthful advertising of a lawful activity (casino gambling is legal in Puerto Rico) raised serious First Amendment problems, but Rehnquist thought otherwise.

"It would . . . surely be strange constitutional doctrine," he said, "which would concede to the legislature the authority to totally ban a product . . . but to deny the legislature the authority" to ban the advertising of it.

As a clerk, Rehnquist also voiced little sympathy for Jehovah's Witnesses who were convicted in New Hampshire and Rhode Island for insisting on making speeches in city parks in violation of local ordinances.

"I personally don't see why a city can't set aside a park for ball games, picnics or other group activities without having some outlandish group like Jehovah's Witnesses commandeer the space and force their message on everyone," Rehnquist said. "Nevertheless, these points raised have not been passed upon by the ct court , and appellants are certainly entitled to a hearing."

Rehnquist's distaste for lawmaking by the courts stood out sharply in a "cert memo" frowning on the Federal Power Commission's claims of exclusive rate-making jurisdiction in a dispute with California's Public Utility Commission. He said "those who want more federal regulation" would probably agree with the FPC's claims about a key clause in the Federal Power Act, but Rehnquist found the claims painfully strained.

" . . . (T)o a devotee of the 'plain meaning' school such as myself -- a school to which I think you are sympathetic -- this is plain unvarnished judicial legislation," Rehnquist told Jackson.

As his opinions from the bench have shown, Rehnquist cannot resist humorous touches -- and he was the same way as a clerk, signing off in one memo as "your obedient servant" and alluding to his fellow clerk in another as "Mr. Justice Cronson." He titled another, recommending tighter rules on petitions for habeas corpus, "Habeas Corpus, Then and Now -- Or, 'If I Can Just Find the Right Judge, Over These Prison Walls I Shall Fly . . . . ' " In it and a companion memo, he argued that it had become too easy for prisoners to go to federal court with charges of maltreatment at the hands of the states.

"In the fields of liberty as well as property, the states must be left to work out their destinies within broad limits," Rehnquist said. "If innocent people are regularly sent to jail, this ct or other federal cts may intervene; but subject to that limitation, there is no more reason for making this ct or other federal cts into a 'super legal aid society' than there was for elevating the doctrine of freedom of contract into a constitutional principle." 'Relax the Federal Grip'

His belief that the Supreme Court should "relax the federal grip on state criminal justice" was also evident in Stein v. New York, in which a state jury had found three men guilty of murdering a Reader's Digest truck driver during a 1950 robbery. The evidence included written confessions from two of the men, but their attorneys contended that the statements had been beaten out of them.

The defendants did not testify, but the prison doctor who examined them reported that the one who did not confess had a broken rib and bruises and abrasions on his side. Another had "bruises on the chest, stomach, right arm, and both buttocks." The third had a bruise on his right arm. The two who confessed did so after about 12 hours of interrogation over a 32-hour period. All three were sentenced to death.

Cronson said he found it "impossible to reach any other conclusion than that these guys were beat up," but Rehnquist argued that there was plenty of other evidence to sustain the convictions even if the confessions were inadmissible. The rule of "harmless error," he argued, should be applied. The defendants had not taken the stand in their own behalf and almost all their efforts were aimed at showing that the confessions had been coerced.

"On this state of the record," Rehnquist wrote, "the conclusion must be that the admission of the confessions was not prejudicial in any rational meaning of that word . . . . The recent eagerness of this court to seize upon coerced confessions is reflected in the trial below. The defendants, instead of attempting to prove their innocence, devoted their time to proving the confessions were coerced. The ivory-tower jurisprudence of the Murphy-Rutledge era Justices Francis W. Murphy and Wiley B. Rutledge were liberal Roosevelt appointees, both of whom died in 1949 has weakened local law enforcement, and if this case is an indication, has saved few innocent men. It has been a boon to smart criminal lawyers, and has supplied this court with a number of cases. Let's hope it has come to an end."

The court, in an opinion written by Jackson, upheld the convictions. Annoyance With Rosenberg 'Antics'

The Rosenberg case, meanwhile, kept coming back, prolonging the 1953 term until the couple was finally executed. At one point, Rehnquist voiced annoyance with the repeated petitions.

"After the antics that ptrs the petitioners have been through in the interim between their last petition here and the present time, I think I would recommend a deny if the trial judge had refused them a hearing on allegations that they had been put on the rack before trial," he wrote. "Fortunately for my sense of judicial impartiality, I am not called upon to make a recommendation in such an extreme case; the case which they present is one which even a sympathetic listener would be constrained to deny on the merits."

The Jackson papers have been at the Library of Congress for less than two years. The only Rehnquist memo among them that came to light during his 1971 confirmation proceedings was the one dealing with "separate but equal" doctrine.

Rehnquist authored two others dealing with black voting rights in Texas, one of which said "it is about time the court faced the fact that the white people in the South don't like the colored people." This one, the complete text shows, is identified by Rehnquist as a statement of Jackson's ideas, "the ideas which you expressed last week," but Dennis Hutchinson, a Jackson scholar from the University of Chicago, said he does not think Jackson ever would have made such a remark.

"That's Rehnquist's way of casting Jackson's ideas," Hutchinson said in a telephone interview. "I can imagine Jackson saying, 'look, there is just a personal animosity between the races in the South,' " Hutchinson said, "but not, 'It is about time the court faced the fact that the white people in the South don't like the colored people.' "

The Jackson papers offer what may be another insight into the unsettled controversy over the "separate but equal" memo. In 1971, Cronson, by then a lawyer with Mobil Oil, sent a cable saying that the memo had been prepared at Jackson's request as a counter to a Cronson memo contending that the doctrine was wrong. Cronson also said that much of the memo Rehnquist signed was actually "the result of my suggestions" and probably "more mine than" Rehnquist's.

Other memos in the Jackson collection, such as those on the Mezei case, show, however, that Cronson and Rehnquist sometimes submitted competing memos, and when they collaborated, they made their collaboration plain. For example, a memo on an antitrust case involving the New Orleans Times-Picayune was clearly labeled as a joint product, with the section Cronson wrote marked "DC" and the Rehnquist section prefaced, "The next type you see will be that of WHR."

There were no such distinctions in the "separate but equal" memo that Rehnquist initialed.

Rehnquist finished his clerkship with Jackson in July 1953 and went to Arizona to begin private practice. But he still exchanged letters with "the Boss." One of them expressed disappointment with President Dwight D. Eisenhower's 1953 nomination of Earl Warren as chief justice.

"Most everyone here was quite disappointed by the nomination of Warren to the Chief Justiceship," Rehnquist wrote Jackson in the spring of 1954 after Warren had been confirmed. "(P)erhaps this is unfair to the man, since there certainly is no affirmative blot on the record. But I cannot help choking every time I hear the line peddled by, among others, Time magazine, to the effect that 'what the court really needs is not so much a lawyer as an administrator and conciliator.'

"What the court really needs," Rehnquist declared, "is a chief justice; an ability to handle the administrative side and to compromise dissidence would be an asset to an able, experienced lawyer in the job, but they certainly are no substitute for some experience in the forums whose actions he is called on to review, nor for the ability to think and write about law.

"I think the few opinions of Warren's I have seen have not been very good," Rehnquist added, "but I don't suppose one should hold that against him; maybe writing opinions is an art for which the knack is acquired."

Staff researcher James Schwartz contributed to this report.