WASHINGTON -- Justice David H. Souter went to th Supreme Court trailing a White House prediction that his selection would be a "home run" for the conservative cause. He )) is proving much of the time -- at least by his votes -- that that isn't necessarily so.

So far in his first term -- about a third of the way through the expected decisions -- he has tended to line up most often with Justice Sandra Day O'Connor, who seems increasingly to lead a moderate bloc that often controls outcomes.

Of the 40 rulings the court has issued up to this point, 16 stood out as the most important, and Justice Souter voted on 13 of those. He was in the majority every time; the only other justice always in the majority in those: Justice O'Connor. (In fact, she took part in all 16 and did not dissent in any.)

Thomas Rath, a Concord, N.H., lawyer and one of Justice Souter's closest friends, remarked in a telephone interview: "I thought he would be somewhere in the middle of that court and in a position to give himself a lot of room for movement." That, he added, is exactly what he has seen happening. "He seeks his own spot."

The newest justice, according to his friend, "is turning out to be somewhat unpredictable -- and reasonable, with no preset ideologies." Recalling that many of the liberal organizations that had fought Justice Souter's nomination worried over what he had not revealed about his views, Mr. Rath said the justice has demonstrated that there was no hidden agenda he was waiting to implement.

Justice Souter has yet to dissent in any case and has written only one opinion, so most of the evidence of his positioning comes from the votes he has cast to support the majority view in a variety of key cases and from the moderate views that have seemed to emerge as he questions lawyers in public hearings.

The justices with whom he has voted least often on key cases are the four on the two philosophical ends of the court: the most conservative, Chief Justice William H. Rehnquist and Justice Antonin Scalia, and the most liberal, Justices Thurgood Marshall and John Paul Stevens.

Some of the conservative organizations that ultimately supported Justice Souter's nomination had hoped he would move rapidly intothe Rehnquist-Scalia bloc, and private assurances from White House Chief of Staff John H. Sununu apparently bolstered that expectation.

In fact, some of President Bush's most fervent conservative followers had supported another candidate for the court vacancy last year -- Circuit Judge Edith H. Jones of Houston, who has established one of the most conservative records of any federal appeals judge. Justice Souter was chosen by the president over her at the last minute, and conservatives fretted privately, until Mr. Sununu provided a reassuring word.

At his Senate nomination hearings, however, Justice Souter took positions that strongly indicated that he would be more moderate than Judge Jones. That seems to be the case, according to his votes up to now.

Often, a justice's leaning is best measured by votes cast in a 5-4 ruling: the toughest cases for the court to decide.

Justice Souter has gone both ways on two major criminal law rulings so far this term. He supported Justice O'Connor, over the dissents of four conservatives, when she wrote a ruling in January enhancing death row inmates' prospects for overturning their sentences on appeal, and he supported the chief justice, over the dissents of four moderate or liberal justices, in a decision allowing some guilty verdicts to stand even though they were based in part on confessions forced out of suspects unconstitutionally.

In two 6-3 key decisions interpreting federal civil rights law, he alsowas found lining up with differing blocs. He supported Justice Harry A. Blackmun's broad ruling favoring a right for female workers of childbearing years to decide for themselves whether to take jobs that might be hazardous to fetuses they might carry, but he supported the chief justice's restrictive decision denying the use of American law to assure equality on the job for U.S. workers in overseas plants or offices of U.S. companies.

Neither vote surprised Mr. Rath. "He decides the case in front of him -- that always makes him hard to predict -- instead of being out there looking for an ideological position and fitting himself into it."

A few times, Justice Souter's votes and public actions have drawn him noticeably away from Justice Scalia, who is commonly considered to be the most determinedly conservative member of the court, and the chief justice, who ranks next to Justice Scalia in that measure.

In two significant cases, when the court gave illegal alien farm workers a new chance to stay in this country under federal "amnesty," and when it narrowed further the rights of prosecutors to shape the racial makeup of criminal trial juries, Justice Souter was in the majority, while only the chief justice and Justice Scalia dissented.

In public hearings, during which the chief justice and Justice Scalia often press their conservative views openly, Justice Souter has asked questions that offered little hint of where his inclinations were taking him.

In a recent case involving the rights of the press, the newest justice and Justice O'Connor asked questions suggesting that the court need not decide the constitutional issue at stake, in marked contrast to deeply skeptical questions from the chief justice and Justice Scalia about the claims being made for the press.

Justice Souter's writing for the court has been limited so far to a unanimous criminal law decision breaking no new legal ground but giving a convicted murderer on death row in Georgia a chance to gain a new trial.

It is traditional for a new justice's first writing assignment to be in an uncomplicated case on which the court was unanimous.

The new justice has told friends that he considers himself to be a slow draftsman of court opinions; he almost surely will be issuing more before the term ends in late June or early July.

"He tends to constantly re-edit and rewrite: He is tough on himself," said his friend, Mr. Rath.

Because he has cast no dissenting votes in any of the 30 decisions inwhich he has taken part, he has written no dissenting opinions; justices often use their writings in dissent to put personal views and individualistic style on public display.

The votes of Justice Souter

Supreme Court Justice David H. Souter has voted in 13 of the court's most significant rulings in his first term, producing this pattern of decisions:

* 5-4 decisions

OPINION: State appeals court must examine on their own, and with care, all evidence that might indicate a death sentence was not justified in a given murder case. AUTHOR: O'Connor

MAJORITY: Souter, Blackmun, Marshall, Stevens

DISSENTING: White, Kennedy, Rehnquist, Scalia

OPINION: Criminal convictions based partly on forced confessions need not be nullified, if there was so much evidence of guilt that the jury would have convicted anyway. AUTHOR: Rehnquist

MAJORITY: Souter, Kennedy, O'Connor, Scalia

DISSENTING: White, Blackmun, Marshall, Stevens

OPINION: Federal courts may punish lawyers' clients as well as lawyers themselves for making frivolous legal claims in court. AUTHOR: O'Connor

MAJORITY: Souter, Blackmun, Rehnquist, White

DISSENTING: Kennedy, Marshall, Scalia, Stevens

* 6-3 decisions

OPINION: Federal civil rights law gives working women a clear right to decide for themselves whether to hold hazardous jobs, even at risk to the health of future fetuses. AUTHOR: Blackmun

MAJORITY: Souter, Marshall, O'Connor, Scalia, Stevens

DISSENTING: White (partly), Kennedy, Rehnquist

OPINION: U.S. civil rights law does not protect American workers from on-the-job sex, race or religious discrimination when they work overseas for U.S. companies. AUTHOR: Rehnquist

MAJORITY: Souter, Kennedy, O'Connor, Scalia, White

DISSENTING: Marshall, Blackmun, Stevens

OPINION: Winners of civil rights lawsuits are not entitled to recover the fees they paid to hire expert witnesses to help them win. AUTHOR: Scalia

MAJORITY: Souter, Kennedy, O'Connor, Rehnquist, White

DISSENTING: Stevens, Blackmun, Marshall

OPINION: City officials have immunity to antitrust lawsuits for official government actions, even the enactment of laws to help one business shut out a rival company. AUTHOR: Scalia

MAJORITY: Souter, Blackmun, O'Connor, Kennedy, Rehnquist

DISSENTING: Stevens, Marshall, White

* 7-2 decisions

OPINION: Whites on trial for crimes have a constitutional right to object when prosecutors keep blacks from serving on juries. AUTHOR: Kennedy

MAJORITY: Souter, Blackmun, O'Connor, Marshall, Stevens, White

DISSENTING: Scalia, Rehnquist

OPINION: Illegal alien farm workers have a right to fair procedures to determine whether they are eligible to stay in this country. AUTHOR: Stevens

MAJORITY: Souter, Blackmun, Kennedy, O'Connor, Marshall, White

DISSENTING: Rehnquist, Scalia

OPINION: Federal civil rights laws give individuals a broad right to sue state and local government officials for interfering with the individuals' interstate business dealings. AUTHOR: White

MAJORITY: Souter, Blackmun, O'Connor, Marshall, Scalia, Stevens

DISSENTING: Kennedy, Rehnquist

OPINION: The United States may set aside workers' rights under labor contracts if necessary to ensure the economic success of a railroad merger. AUTHOR: Kennedy

MAJORITY: Souter, Blackmun, O'Connor, Rehnquist, Scalia, White

DISSENTING: Stevens, Marshall

* Unanimous decisions

OPINION: Federal regulators may not be sued for damages for the harm they cause when they intervene to make day-to-day business decisions for a government-regulated company. AUTHOR: White

OPINION: Federal law requires labor unions to allow dissident candidates in union elections to send out their campaign leaflets to the members. AUTHOR: Stevens