Some Republicans on the panel had said that a speech Sotomayor gave in 2001, in which she said a "wise Latina" might reach a better legal decision than a white man, was evidence that she is biased in favour of Hispanics.
Sotomayor said that the comments, which were made in several addresses to women's and Hispanic legal groups, were aimed at motivating young people to enter the legal profession.
"I was trying to inspire them to believe that their life experiences would enrich the legal system, because different life experiences and backgrounds always do," she said.
The nominee also defended her recent ruling on a US appeals court panel which said that the city of New Haven in Connecticut could disregard a promotion exam for firefighters because too few black candidates passed it.
"We were following precedent," she said of her ruling, which was overturned by the US supreme court last month.
Balance of power
Senator Jeff Sessions, the leading Republican on the committee, asked her if she believed that "impartiality is a mere aspiration which may not be possible in all or even most cases".
But Sotomayor said that her life experience was of no import in making judicial rulings, emphasising that the tenets of the law should be observed.
"I believe my record of 17 years demonstrates fully that I do believe that judges must apply the law and not make the law," Sotomayor said.
Democrats, who have control of the senate, say that Sotomayor is the ideal candidate for to serve on the nine-member supreme court.
The court has been closely divided with four liberal and five conservative members, and Sotomayor’s confirmation as the replacement to Justice David Souter would ensure that such a balance would remain.