In her sophomore year, Sotomayor walked into the office of university President William G. Bowen to demand more Latino faculty and students. Not satisfied with his response, she and others filed a complaint with the federal government, accusing the school administration of "an institutional pattern of discrimination."
"The facts imply and reflect the total absence of regard, concern and respect for an entire people and their culture," she wrote in the Daily Princetonian.
Sotomayor, considered a brilliant student, graduated summa cum laude from the Ivy League school in 1976. While there, she was a passionate advocate for minorities and displayed an intense interest in her heritage: Her parents had moved to New York from Puerto Rico before she was born.
From Princeton onward, a look at her life has shown, she has viewed the law as a tool for social empowerment.
But critics of Sotomayor's Supreme Court nomination fear that as a justice she would take that concern too far, siding with the underdog as a matter of principle rather than on the basis of cleareyed legal judgment.
"It is perfectly appropriate for people to bring their life experience to their judging," said John C. Eastman, a former clerk to Supreme Court Justice Clarence Thomas who now serves as dean of the Chapman University School of Law in Orange. "But there's a difference between having that perspective and being able to put one thumb on the scale to benefit one group over another."
After Princeton, at Yale Law School, as a prosecutor and a corporate lawyer in New York, and while serving as a federal judge for 17 years, Sotomayor continued to display a passion for minority rights. She was active on the board of directors of the Puerto Rican Legal Defense and Education Fund when it sued New York City over alleged discrimination in police hiring and the drawing of voting districts, as well as when it challenged New York state's death penalty law.
Eight years ago, while sitting on the federal appeals court in New York on which she still serves, Sotomayor said it was "shocking" that there were not more minority women on the federal bench.
But little of that activist sentiment is revealed in the hundreds of cases Sotomayor has decided in her 11 years on the U.S. 2nd Circuit Court of Appeals, raising the question of which jurist will present herself if she is given the lifetime tenure and complete independence of a Supreme Court seat.
Thomas Goldstein, a Washington lawyer with a Supreme Court specialty, said last week that he had reviewed 50 appeals involving race in which Sotomayor participated. In 45 of those cases, a three-judge panel rejected the discrimination claim -- and Sotomayor never once dissented, he said.
"This is a judge who does not see it as her job to fix all the social ills in the world," said Kevin Russell, a Washington appellate lawyer who also has analyzed Sotomayor's opinions.
But in her 1974 letter to the student newspaper, Sotomayor complained that the university had no faculty members of Puerto Rican or Mexican descent. The incoming freshman class that year numbered 1,141. Of those, 36 were Latino. The inequities she felt she confronted there cut her deeply, friends said.
In her junior year, Princeton tapped Sotomayor to serve on a student committee that advised the administration on replacing an outgoing dean dedicated to minority issues.
But she grew disillusioned with the assignment. She objected that her committee had little power to influence the selection. In a 1974 article in the Daily Princetonian, Sotomayor was quoted as saying: "We were token students, period. The decision was made without consulting us.
"What we in effect want is for the school to realize we're not here to play patsies, we're not a front."
On campus, she was active in Accion Puertorriquena, which served as a kind of social and political center for Latino students.
She spoke up for gays who were being harassed on campus. One of her public policy professors, Jameson Doig, recalls that she also spoke out against police abuse.
"Police brutality was an area that was of greater concern to those who are familiar with poorer areas in New York. She was an articulate person in expressing concerns about that kind of misbehavior and in suggesting ways that one could reduce problems of police and public housing violence," Doig said.