In one session of oral arguments after another--on subjects as diverse as voting rights, drug paraphernalia and the Federal Mine Safety Act--the new justice peppered competing attorneys with dozens of polite but pointed questions.
She poked large holes in arguments put forth by prominent Washington lawyers. During several sessions, she clarified where the two sides actually disagreed. In nearly every instance, she displayed a remarkable grasp of the law and the thick records from lower courts.
"You are relying a lot on Abbott Labs," she told an attorney representing a non-union Wyoming coal mine that seeks to keep union members off a federal safety inspection team. She was referring to a 1967 high court decision that set rules on when employers can go directly to court to protest a federal regulatory decision.
"But Abbott came as part of a trilogy, and your case seems a lot closer to the situation in the Toilet Goods case," Ginsburg said.
The attorney paused, seemingly unsure how the second case differed. For the rest of his half-hour appearance, he backpedaled before a barrage of inquiries from Ginsburg.
But the government's lawyer did not have an easy time either.
"Why are you putting so much weight on a case you mentioned only once, in footnote 25 of your brief?" she asked at one point.
Ginsburg's snappy style and impressive grasp of the legal complexities stands in sharp contrast to virtually all other newcomers to the court. Typically, rookies sit quietly on the bench, listening but adding little to the arguments.
Because of the heavy work load, most new justices say it takes a year or more to feel comfortable during the arguments.
In 1990, Justice David H. Souter did not ask a single question during his first month on the bench, although he has since emerged as one of the court's most thoughtful interrogators.
In recent years, only Justice Antonin Scalia, a 1986 appointee of former President Ronald Reagan, has been an assertive member of the court from the beginning.
But even the irrepressible Scalia did not match Ginsburg's first week on the bench.
Ginsburg's performance contrasts vividly to that of Justice Clarence Thomas, the justice who preceded her to the court. Thomas rarely participates in the arguments.
Now beginning his third year on the bench, Thomas usually rocks back in his chair and seemingly pays little attention to the arguments. In three days on the bench this week, he did not ask a single question.
While Ginsburg quizzed the lawyers in the mine safety case, Thomas rubbed his eyes often and gazed at the ornate ceiling.
Several veteran lawyers who sat in the courtroom this week came away impressed with the new justice.
"She was incredible," said one who sat through three hours of argument on Monday in which Ginsburg asked 46 questions. "She was very pointed in focusing the cases--not berating the attorneys but narrowing the issues. And she was totally on top of the record," he said.
Gone was the hesitant manner the 60-year judge displayed at times during her Senate confirmation hearings in July. Speaking in a voice that cut through the courtroom, Ginsburg asked direct, precise questions this week. When an attorney dodged the issue, she persisted.
On Wednesday morning, her repeated inquiries appeared to tilt an argument in favor of the parents of a learning-disabled child.
At first, the case of Florence County vs. Shannon Carter appeared to give the court a chance to rein in the soaring cost of special education. The justices had agreed to hear an appeal from a South Carolina school district that had been ordered to reimburse the parents of a learning-disabled child the $36,000 cost of three years of private schooling.
But from the opening minute, Ginsburg went on the attack, and the school district's lawyer was sent reeling.
The girl's parents had been frustrated, first that the public school officials failed to diagnose her severe learning disorder and later when they failed to offer her full-time special help.
While conceding the school system's failure, Donald B. Ayer, a former U.S. deputy solicitor general now representing Florence County, argued that the parents should not be reimbursed because they made a "unilateral" decision to seek private schooling.
"But the school system has not provided the education the (federal) statute requires. What's the remedy for the parents?" Ginsburg asked.
Ayer suggested that the parents should have tried harder to find an acceptable program in the public school system.
"If the school district was in default, why should the burden be on the parents?" Ginsburg countered.
Souter and Scalia joined in with skeptical questions.
"Isn't the (federal) law for the benefit of the children, so they don't get stuck in a second-rate program?" Souter asked.
Scalia chimed in: "Who did Congress distrust when they passed this law (mandating special education for disabled children)? School boards or parents? You don't think they distrusted parents to do the right thing by their children?" he asked.
By the end of the hour, a solid majority of the court sounded ready to reject the school board's claim.