"In the past month, many senators have asked me about my judicial philosophy. It is simple: fidelity to the law. The task of a judge is not to make the law - it is to apply the law."
Patrick Leahy, a Democrat and the chairman of the committee, had earlier urged the panel to focus solely on Sotomayor's career record.
"Let no-one demean this extraordinary woman, her success," and her acheivements, he said as the first day of the four-day hearing got under way.
"She understands that there is not one law for one race or another. There is not one law for one colour or another. There is not one law for rich and a different one for poor. There is only one law."
Rosalind Jordan, Al Jazeera's US correspondent, said that panel Republicans who are sceptical of Sotomayor's record will have to move carefully, given that she is vying to become the supreme court's first Latina judge.
"Congressional elections are about 18 months away and the Republican party, which has been leading much of the criticism about Sotomayor, are facing a lot of difficulties with Latino residents in the United States," she said.
"They took a real beating for fighting immigration reform during the last presidency and they are very concerned that they might lose more congressional seats if they go after Sotomayor in any substantial way."
If confirmed, the 55-year-old appeals court judge would replace retiring Justice David Souter.
'Brave new world'
But Jeff Sessions, the leading Republican senator on the committee, said that Sotomayor still had to convince him that she would be impartial in her interpretation of the law.
"The strategy is to be as thorough as we can in examining her record, what she has said, and to conduct the hearings in a fair, impartial, and thorough way"
Jon Kyl, Republican senator
"Down the other path lies a brave new world, where words have no true meaning, and judges are free to decide what facts they choose to see," he said.
"In this world, a judge is free to push his or her own political or social agenda."
Sotomayor will face questions from the panel on Tuesday.
Louis Freeh, a former FBI director who mentored Sotomayor, and Linda Chavez, a conservative activist, will also address the committee over the course of the hearing.
Experts say the Democrats have the 60 senate votes needed to prevent any Republican effort to use delaying tactics to block Sotomayor's nomination.
Republicans have given one of their 14 witness slots to one of the white firefighters whose claim of racial discrimination in a job application Sotomayor rejected.
The supreme court reversed her ruling in late June.
Senator Jon Kyl, reported to be leading the Republican strategy for the confirmation hearings, told the ABC news channel that Sotomayor would get a fair hearing.
"The strategy is to be as thorough as we can in examining her record, what she has said and to conduct the hearings in a fair, impartial and thorough way - and then make our decisions."
Sotomayor's rise from a poor childhood in the Bronx in New York to the height of US justice mirrors Obama's own ascent to power.
Upon announcing her nomination, Obama declared that Sotomayor could boast a "brilliant legal career" and "the wisdom accumulated from an inspiring life's journey".
If appointed, Sotomayor, would be the second woman currently on the court, alongside Justice Ruth Bader Ginsburg.