Sotomayor was raised a Catholic and grew up in Puerto Rican communities in the South Bronx and East Bronx; she self-identifies as a “Nuyorican”. The family lived in a South Bronx tenement before moving in 1957 to the well-maintained, racially and ethnically mixed, working-class Bronxdale Houses housing project in Soundview (which has over time been thought as part of both the East Bronx and South Bronx). Her relative proximity to Yankee Stadium led to her becoming a lifelong fan of the New York Yankees. The extended family got together frequently and regularly visited Puerto Rico during summers.

Celina Sotomayor put great stress on the value of education; she bought the Encyclopædia Britannica for her children, something unusual in the housing projects. Despite the distance between the two, which became greater after her father’s death and which was not fully reconciled until decades later, Sotomayor has credited her mother with being her “life inspiration”. For grammar school, Sotomayor attended Blessed Sacrament School in Soundview, where she was valedictorian and had a near-perfect attendance record. Although underage, Sotomayor worked at a local retail store and a hospital. Sotomayor passed the entrance tests for and then attended Cardinal Spellman High School in the Bronx. At Cardinal Spellman, Sotomayor was on the forensics team and was elected to the student government. She graduated as valedictorian in 1972. Meanwhile, the Bronxdale Houses had fallen victim to increasing heroin use, crime, and the emergence of the Black Spades gang. In 1970, the family found refuge by moving to Co-op City in the Northeast Bronx.

As an activist, Sotomayor focused on faculty hiring and curriculum, since Princeton did not have a single full-time Latino professor nor any class on Latin American studies. A meeting with university president William G. Bowen in her sophomore year saw no results, leading to Sotomayor’s saying in a New York Times story at the time that “Princeton is following a policy of benign neutrality and is not making substantive efforts to change.” So, Acción Puertorriqueña filed a formal letter of complaint in April 1974 with the Department of Health, Education and Welfare, saying the school discriminated in its hiring and admission practices. Sotomayor wrote opinion pieces for the Daily Princetonian with the same theme. The university began to hire Latino faculty, and Sotomayor established an ongoing dialogue with Bowen. Sotomayor also successfully persuaded historian Peter Winn to create a seminar on Puerto Rican history and politics. Sotomayor joined the governance board of Princeton’s Third World Center and served on the university’s student–faculty Discipline Committee, which issued rulings on student infractions. She also ran an after-school program for local children and volunteered as an interpreter for Latino patients at Trenton Psychiatric Hospital.

Academically, Sotomayor stumbled her first year at Princeton, but later received almost all A’s in her final two years of college. Sotomayor wrote her senior thesis at Princeton on Luis Muñoz Marín, the first democratically elected governor of Puerto Rico, and on the territory’s struggles for economic and political self-determination. The 178-page work, “La Historia Ciclica de Puerto Rico: The Impact of the Life of Luis Muñoz Marin on the Political and Economic History of Puerto Rico, 1930–1975”, won honorable mention for the Latin American Studies Thesis Prize. As a senior, Sotomayor won the Pyne Prize, the top award for undergraduates, which reflected both strong grades and extracurricular activities. In 1976, she was elected to Phi Beta Kappa and graduated summa cum laude with an A.B. in history. She was influenced by critical race theory, which would be reflected in her later speeches and writings.

On August 14, 1976, just after graduating from Princeton, Sotomayor married Kevin Edward Noonan, whom she had dated since high school, in a small chapel at St. Patrick’s Cathedral in New York. She used the married name Sonia Sotomayor de Noonan. He became a biologist and a patent lawyer.

In 1979, Sotomayor was awarded a Juris Doctor from Yale Law School. She was admitted to the New York Bar the following year.

On the recommendation of Cabranes, Sotomayor was hired out of law school as an assistant district attorney under New York County District Attorney Robert Morgenthau starting in 1979. She said at the time that she did so with conflicted emotions: “There was a tremendous amount of pressure from my community, from the third world community, at Yale. They could not understand why I was taking this job. I’m not sure I’ve ever resolved that problem.” It was a time of crisis-level crime rates and drug problems in New York, Morgenthau’s staff was overburdened with cases, and like other rookie prosecutors, Sotomayor was initially fearful of appearing before judges in court. Working in the trial division, she handled heavy caseloads as she prosecuted everything from shoplifting and prostitution to robberies, assaults, and murders. She also worked on cases involving police brutality. She was not afraid to venture into tough neighborhoods or endure squalid conditions in order to interview witnesses. In the courtroom, she was effective at cross examination and at simplifying a case in ways to which a jury could relate. In 1983, she helped convict Richard Maddicks (known as the “Tarzan Murderer” who acrobatically entered apartments, robbed them, and shot residents for no reason). She felt lower-level crimes were largely products of socioeconomic environment and poverty, but she had a different attitude about serious felonies: “No matter how liberal I am, I’m still outraged by crimes of violence. Regardless of whether I can sympathize with the causes that lead these individuals to do these crimes, the effects are outrageous.” Hispanic-on-Hispanic crime was of particular concern to her: “The saddest crimes for me were the ones that my own people committed against each other.” In general, she showed a passion for bringing law and order to the streets of New York, displaying special zeal in pursuing child pornography cases, unusual for the time. She worked 15-hour days and gained a reputation for being driven and for her preparedness and fairness. One of her job evaluations labelled her a “potential superstar”. Morgenthau later described her as “smart, hard-working, [and having] a lot of common sense,” and as a “fearless and effective prosecutor.” She stayed a typical length of time in the post and had a common reaction to the job: “After a while, you forget there are decent, law-abiding people in life.”

Sotomayor and Noonan divorced amicably in 1983; they did not have children. She has said that the pressures of her working life were a contributing factor, but not the major factor, in the breakup. From 1983 to 1986, Sotomayor had an informal solo practice, dubbed Sotomayor & Associates, located in her Brooklyn apartment. She performed legal consulting work, often for friends or family members.

In 1984, she entered private practice, joining the commercial litigation practice group of Pavia & Harcourt in Manhattan as an associate. One of 30 attorneys in the law firm, she specialized in intellectual property litigation, international law, and arbitration. She later said, “I wanted to complete myself as an attorney.” Although she had no civil litigation experience, the firm recruited her heavily, and she learned quickly on the job. She was eager to try cases and argue in court, rather than be part of a larger law firm. Her clients were mostly international corporations doing business in the United States; much of her time was spent tracking down and suing counterfeiters of Fendi goods. In some cases, Sotomayor went on-site with the police to Harlem or Chinatown to have illegitimate merchandise seized, in the latter instance pursuing a fleeing culprit while riding on a motorcycle. She said at the time that Pavia & Harcourt’s efforts were run “much like a drug operation”, and the successful rounding up of thousands of counterfeit accessories in 1986 was celebrated by “Fendi Crush”, a destruction-by-garbage-truck event at Tavern on the Green. At other times, she dealt with dry legal issues such as grain export contract disputes. In a 1986 appearance on Good Morning America that profiled women ten years after college graduation, she said that the bulk of law work was drudgery, and that while she was content with her life, she had expected greater things of herself coming out of college. In 1988 she became a partner at the firm; she was paid well but not extravagantly. She left in 1992 when she became a judge.

During 1985 and 1986, Sotomayor served on the board of the Maternity Center Association, a Manhattan-based non-profit group which focused on improving the quality of maternity care.

In addition to her law firm work, Sotomayor found visible public service roles. She was not connected to the party bosses that typically picked people for such jobs in New York, and indeed she was registered as an independent. Instead, District Attorney Morgenthau, an influential figure, served as her patron. In 1987, Governor of New York Mario Cuomo appointed Sotomayor to the board of the State of New York Mortgage Agency, which she served on until 1992. As part of one of the largest urban rebuilding efforts in American history, the agency helped low-income people get home mortgages and to provide insurance coverage for housing and hospices for sufferers of AIDS. Despite being the youngest member of a board composed of strong personalities, she involved herself in the details of the operation and was effective. She was vocal in supporting the right to affordable housing, directing more funds to lower-income home owners, and in her skepticism about the effects of gentrification, although in the end she voted in favor of most of the projects.

Sotomayor was appointed by Mayor Ed Koch in 1988 as one of the founding members of the New York City Campaign Finance Board, where she served for four years. There she took a vigorous role in the board’s implementation of a voluntary scheme wherein local candidates received public matching funds in exchange for limits on contributions and spending and agreeing to greater financial disclosure. Sotomayor showed no patience with candidates who failed to follow regulations and was more of a stickler for making campaigns follow those regulations than some of the other board members. She joined in rulings that fined, audited, or reprimanded the mayoral campaigns of Koch, David Dinkins, and Rudy Giuliani.

Sotomayor had wanted to become a judge since she was in elementary school, and in 1991 she was recommended for a spot by Democratic New York senator Daniel Patrick Moynihan. Moynihan had an unusual bipartisan arrangement with his fellow New York senator, Republican Al D’Amato, whereby he would get to choose roughly one out of every four New York district court seats even though a Republican was in the White House. Moynihan also wanted to fulfill a public promise he had made to get a Hispanic judge appointed for New York. When Moynihan’s staff recommended her to him, they said “Have we got a judge for you!” Moynihan identified with her socio-economic and academic background and became convinced she would become the first Hispanic Supreme Court justice. D’Amato became an enthusiastic backer of Sotomayor, who was seen as politically centrist at the time. Of the impending drop in salary from private practice, Sotomayor said: “I’ve never wanted to get adjusted to my income because I knew I wanted to go back to public service. And in comparison to what my mother earns and how I was raised, it’s not modest at all.”

Sotomayor was thus nominated on November 27, 1991, by President George H. W. Bush to a seat on the U.S. District Court for the Southern District of New York vacated by John M. Walker Jr. Senate Judiciary Committee hearings, led by a friendly Democratic majority, went smoothly for her in June 1992, with her pro bono activities winning praise from Senator Ted Kennedy and her getting unanimous approval from the committee. Then a Republican senator blocked her nomination and that of three others for a while in retaliation for an unrelated block Democrats had put on another nominee. D’Amato objected strongly; some weeks later, the block was dropped, and Sotomayor was confirmed by unanimous consent of the full United States Senate on August 11, 1992, and received her commission the next day.

On March 30, 1995, in Silverman v. Major League Baseball Player Relations Committee, Inc., Sotomayor issued a preliminary injunction against Major League Baseball, preventing it from unilaterally implementing a new collective bargaining agreement and using replacement players. Her ruling ended the 1994 baseball strike after 232 days, the day before the new season was scheduled to begin. The Second Circuit upheld Sotomayor’s decision and denied the owners’ request to stay the ruling. The decision raised her profile, won her the plaudits of baseball fans, and had a lasting effect on the game. In the preparatory phase of the case, Sotomayor informed the lawyers of both sides that, “I hope none of you assumed … that my lack of knowledge of any of the intimate details of your dispute meant I was not a baseball fan. You can’t grow up in the South Bronx without knowing about baseball.”

She maintains ties with Puerto Rico, visiting once or twice a year, speaking there occasionally, and visiting cousins and other relatives who still live in the Mayagüez area. She has long stressed her ethnic identity, saying in 1996, “Although I am an American, love my country and could achieve its opportunity of succeeding at anything I worked for, I also have a Latina soul and heart, with the magic that carries.”

On June 25, 1997, Sotomayor was nominated by President Bill Clinton to a seat on the U.S. Court of Appeals for the Second Circuit, which was vacated by J. Daniel Mahoney. Her nomination was initially expected to have smooth sailing, with the American Bar Association Standing Committee on the Federal Judiciary giving her a “well qualified” professional assessment. However, as The New York Times described, “[it became] embroiled in the sometimes tortured judicial politics of the Senate.” Some in the Republican majority believed Clinton was eager to name the first Hispanic Supreme Court justice and that an easy confirmation to the appeals court would put Sotomayor in a better position for a possible Supreme Court nomination (despite there being no vacancy at the time nor any indication the Clinton administration was considering nominating her or any Hispanic). Therefore, the Republican majority decided to slow her confirmation. Radio commentator Rush Limbaugh weighed in that Sotomayor was an ultraliberal who was on a “rocket ship” to the highest court.

Sotomayor said of the years following her divorce, that “I have found it difficult to maintain a relationship while I’ve pursued my career.” She has talked of herself as “emotionally withdrawn” and lacking “genuine happiness” when living by herself; after becoming a judge, she said she would not date lawyers. In 1997, she was engaged to New York construction contractor Peter White, but the relationship had ended by 2000.

During her September 1997 hearing before the Senate Judiciary Committee, Sotomayor parried strong questioning from some Republican members about mandatory sentencing, gay rights, and her level of respect for Supreme Court Justice Clarence Thomas. After a long wait, she was approved by the committee in March 1998, with only two dissensions. However, in June 1998, the influential Wall Street Journal editorial page opined that the Clinton administration intended to “get her on to the Second Circuit, then elevate her to the Supreme Court as soon as an opening occurs”; the editorial criticized two of her district court rulings and urged further delay of her confirmation. The Republican block continued.

During 1998, several Hispanic organizations organized a petition drive in New York State, generating hundreds of signatures from New Yorkers to try to convince New York Republican senator Al D’Amato to push the Senate leadership to bring Sotomayor’s nomination to a vote. D’Amato, a backer of Sotomayor to begin with and additionally concerned about being up for re-election that year, helped move Republican leadership. Her nomination had been pending for over a year when Majority Leader Trent Lott scheduled the vote. With complete Democratic support, and support from 25 Republican senators including Judiciary chair Orrin Hatch, Sotomayor was confirmed on October 2, 1998, by a 67–29 vote. She received her commission on October 7. The confirmation experience left Sotomayor somewhat angry; she said shortly afterwards that during the hearings, Republicans had assumed her political beliefs based on her being a Latina: “That series of questions, I think, were symbolic of a set of expectations that some people had [that] I must be liberal. It is stereotyping, and stereotyping is perhaps the most insidious of all problems in our society today.”

Sotomayor was an adjunct professor at New York University School of Law from 1998 to 2007. There she taught trial and appellate advocacy as well as a federal appellate court seminar. Beginning in 1999, she was also a lecturer in law at Columbia Law School in a paying, adjunct faculty position. While there she created and co-taught a class called the Federal Appellate Externship each semester from 2000 until her departure; it combined classroom, moot court, and Second Circuit chambers work. She became a member of the Board of Trustees of Princeton University in 2006, concluding her term in 2011. In 2008, Sotomayor became a member of the Belizean Grove, an invitation-only women’s group modeled after the men’s Bohemian Grove. On June 19, 2009, Sotomayor resigned from the Belizean Grove after Republican politicians voiced concerns over the group’s membership policy.

Sotomayor was a member of the Second Circuit Task Force on Gender, Racial and Ethnic Fairness in the Courts. In October 2001, she presented the annual Judge Mario G. Olmos Memorial Lecture at UC Berkeley School of Law; titled “A Latina Judge’s Voice”; it was published in the Berkeley La Raza Law Journal the following spring. In the speech, she discussed the characteristics of her Latina upbringing and culture and the history of minorities and women ascending to the federal bench. She said the low number of minority women on the federal bench at that time was “shocking”. She then discussed at length how her own experiences as a Latina might affect her decisions as a judge. In any case, her background in activism did not necessarily influence her rulings: in a study of 50 racial discrimination cases brought before her panel, 45 were rejected, with Sotomayor never filing a dissent. An expanded study showed that Sotomayor decided 97 cases involving a claim of discrimination and rejected those claims nearly 90 percent of the time. Another examination of Second Circuit split decisions on cases that dealt with race and discrimination showed no clear ideological pattern in Sotomayor’s opinions.

Sotomayor’s nomination won praise from Democrats and liberals, and Democrats appeared to have sufficient votes to confirm her. The strongest criticism of her nomination came from conservatives and some Republican senators regarding a line she had used in similar forms in a number of her speeches, particularly in a 2001 Berkeley Law lecture: “I would hope that a wise Latina woman with the richness of her experiences would more often than not reach a better conclusion than a white male who hasn’t lived that life.” Sotomayor had made similar remarks in other speeches between 1994 and 2003, including one she submitted as part of her confirmation questionnaire for the Court of Appeals in 1998, but they had attracted little attention at the time. The remark now became widely known. The rhetoric quickly became inflamed, with radio commentator Rush Limbaugh and former Republican Speaker of the House of Representatives Newt Gingrich calling Sotomayor a “racist” (although the latter later backtracked from that claim), while John Cornyn and other Republican senators denounced such attacks but said that Sotomayor’s approach was troubling. Backers of Sotomayor offered a variety of explanations in defense of the remark, and White House Press Secretary Robert Gibbs stated that Sotomayor’s word choice in 2001 had been “poor”. Sotomayor subsequently clarified her remark through Senate Judiciary Committee chair Patrick Leahy, saying that while life experience shapes who one is, “ultimately and completely” a judge follows the law regardless of personal background. Of her cases, the Second Circuit rulings in Ricci v. DeStefano received the most attention during the early nomination discussion, motivated by the Republican desire to focus on the reverse racial discrimination aspect of the case. In the midst of her confirmation process the Supreme Court overturned that ruling on June 29. A third line of Republican attack against Sotomayor was based on her ruling in Maloney v. Cuomo and was motivated by gun ownership advocates concerned about her interpretation of Second Amendment rights. Some of the fervor with which conservatives and Republicans viewed the Sotomayor nomination was due to their grievances over the history of federal judicial nomination battles going back to the 1987 Robert Bork Supreme Court nomination.

In the 2002 decision Center for Reproductive Law and Policy v. Bush, Sotomayor upheld the Bush administration’s implementation of the Mexico City Policy, which states that “the United States will no longer contribute to separate nongovernmental organizations which perform or actively promote abortion as a method of family planning in other nations.” Sotomayor held that the policy did not constitute a violation of equal protection, as “the government is free to favor the anti-abortion position over the pro-choice position, and can do so with public funds.”

She was elected a member of the American Philosophical Society in 2002. She was given the Outstanding Latino Professional Award in 2006 by the Latino/a Law Students Association. In 2008, Esquire magazine included Sotomayor on its list of “The 75 Most Influential People of the 21st Century”. In 2013, Sotomayor won the Woodrow Wilson Award at her alma mater Princeton University.

In Brody v. Village of Port Chester (2003 and 2005), a takings case, Sotomayor first ruled in 2003 for a unanimous panel that a property owner in Port Chester, New York was permitted to challenge the state’s Eminent Domain Procedure Law. A district court subsequently rejected the plaintiff’s claims and upon appeal the case found itself again with the Second Circuit. In 2005, Sotomayor ruled with a panel majority that the property owner’s due process rights had been violated by lack of adequate notice to him of his right to challenge a village order that his land should be used for a redevelopment project. However, the panel supported the village’s taking of the property for public use.

In 2004, Sotomayor was part of the judge panel that ruled in Swedenburg v. Kelly that New York’s law prohibiting out-of-state wineries from shipping directly to consumers in New York was constitutional even though in-state wineries were allowed to. The case, which invoked the 21st Amendment, was appealed and attached to another case. The case reached the Supreme Court later on as Swedenburg v. Kelly and was overruled in a 5–4 decision that found the law was discriminatory and unconstitutional.

In 2005, Senate Democrats suggested Sotomayor, among others, to President George W. Bush as an acceptable nominee to fill the seat of retiring Supreme Court Justice Sandra Day O’Connor.

In 2005, Sotomayor wrote the opinion for United States v. Quattrone. Frank Quattrone had been on trial on charges of obstructing investigations related to technology IPOs. Some members of the media had wanted to publish the names of the jurors deciding Quattrone’s case, and a district court had issued an order to forbid the publication of the juror’s names. In United States v. Quattrone, Sotomayor wrote the opinion for the Second Circuit panel striking down this order on First Amendment grounds, stating that the media should be free to publish the names of the jurors. The first trial ended in a deadlocked jury and a mistrial, and the district court ordered the media not to publish the names of jurors, even though those names had been disclosed in open court. Sotomayor held that although it was important to protect the fairness of the retrial, the district court’s order was an unconstitutional prior restraint on free speech and violated the right of the press “to report freely on events that transpire in an open courtroom”.

In 2008, Sotomayor was on a three-judge panel in Doninger v. Niehoff that unanimously affirmed, in an opinion written by Second Circuit Judge Debra Livingston, the district court’s judgment that Lewis S. Mills High School did not violate the First Amendment rights of a student when it barred her from running for student government after she called the superintendent and other school officials “douchebags” in a blog post written while off-campus that encouraged students to call an administrator and “piss her off more”. Judge Livingston held that the district judge did not abuse her discretion in holding that the student’s speech “foreseeably create[d] a risk of substantial disruption within the school environment”, which is the precedent in the Second Circuit for when schools may regulate off-campus speech. Although Sotomayor did not write this opinion, she has been criticized by some who disagree with it.

Sotomayor was part of the three-judge Second Circuit panel that affirmed the district court’s ruling in Maloney v. Cuomo (2009). Maloney was arrested for possession of nunchucks, which are illegal in New York; Maloney argued that this law violated his Second Amendment right to bear arms. The Second Circuit’s per curiam opinion noted that the Supreme Court has not, so far, ever held that the Second Amendment is binding against state governments. On the contrary, in Presser v. Illinois, a Supreme Court case from 1886, the Supreme Court held that the Second Amendment “is a limitation only upon the power of Congress and the national government, and not upon that of the state”. With respect to the Presser v. Illinois precedent, the panel stated that only the Supreme Court has “the prerogative of overruling its own decisions,” and the recent Supreme Court case of District of Columbia v. Heller (which struck down the district’s gun ban as unconstitutional) did “not invalidate this longstanding principle”. The panel upheld the lower court’s decision dismissing Maloney’s challenge to New York’s law against possession of nunchucks. On June 2, 2009, a Seventh Circuit panel, including the prominent and heavily cited judges Richard Posner and Frank Easterbrook, unanimously agreed with Maloney v. Cuomo, citing the case in their decision turning back a challenge to Chicago’s gun laws and noting the Supreme Court precedents remain in force until altered by the Supreme Court itself.

Sotomayor was involved in the high-profile case Ricci v. DeStefano that initially upheld the right of the City of New Haven to throw out its test for firefighters and start over with a new test, because the City believed the test had a “disparate impact” on minority firefighters. (No black firefighters qualified for promotion under the test, whereas some had qualified under tests used in previous years.) The City was concerned that minority firefighters might sue under Title VII of the Civil Rights Act of 1964. The City chose not to certify the test results and a lower court had previously upheld the City’s right to do this. Several white firefighters and one Hispanic firefighter who had passed the test, including the lead plaintiff who has dyslexia and had put extra effort into studying, sued the City of New Haven, claiming that their rights were violated. A Second Circuit panel that included Sotomayor first issued a brief, unsigned summary order (not written by Sotomayor) affirming the lower court’s ruling. Sotomayor’s former mentor José A. Cabranes, by now a fellow judge on the court, objected to this handling and requested that the court hear it en banc. Sotomayor voted with a 7–6 majority not to rehear it and a slightly expanded ruling was issued, but a strong dissent by Cabranes led to the case reaching the Supreme Court in 2009. There it was overruled in a 5–4 decision that found the white firefighters had been victims of racial discrimination when they were denied promotion.

Following Barack Obama’s 2008 presidential election victory, speculation arose that Sotomayor could be a leading candidate for a Supreme Court seat. New York Senators Charles Schumer and Kirsten Gillibrand wrote a joint letter to Obama urging him to appoint Sotomayor, or alternatively Interior Secretary Ken Salazar, to the Supreme Court if a vacancy should arise during his term. The White House first contacted Sotomayor on April 27, 2009, about the possibility of her nomination. On April 30, 2009, Justice David Souter’s retirement plans leaked to the media, and Sotomayor received early attention as a possible nominee for Souter’s seat to be vacated in June 2009. On May 25, Obama informed Sotomayor of his choice; she later said, “I had my [hand] over my chest, trying to calm my beating heart, literally.” On May 26, 2009, Obama nominated her. She became only the second jurist to be nominated to three different judicial positions by three different presidents. The selection appeared to closely match Obama’s presidential campaign promise that he would nominate judges who had “the heart, the empathy, to recognize what it’s like to be a teenage mom. The empathy to understand what it’s like to be poor, or African-American, or gay, or disabled, or old.”

Sotomayor’s confirmation hearings before the Senate Judiciary Committee began on July 13, 2009, during which she backed away from her “wise Latina” remark, declaring it “a rhetorical flourish that fell flat” and stating that “I do not believe that any ethnic, racial or gender group has an advantage in sound judgment.” When Republican senators confronted her regarding other remarks from her past speeches, she pointed to her judicial record and said she had never let her own life experiences or opinions influence her decisions. Republican senators said that while her rulings to this point might be largely traditional, they feared her Supreme Court rulings – where there is more latitude with respect to precedent and interpretation – might be more reflective of her speeches. Sotomayor defended her position in Ricci as following applicable precedent. When asked whom she admired, she pointed to Justice Benjamin N. Cardozo. In general, Sotomayor followed the hearings formula of recent past nominees by avoiding stating personal positions, declining to take positions on controversial issues likely to come before the Court, agreeing with senators from both parties, and repeatedly affirming that as a justice she would just apply the law.

On July 28, 2009, the Senate Judiciary Committee voted 13–6 in favor of Sotomayor’s nomination, sending it to the full Senate for a final confirmation vote. Every Democrat voted in her favor, as did one Republican, Lindsey Graham. On August 6, 2009, Sotomayor was confirmed by the full Senate by a vote of 68–31. All Democrats present, along with the Senate’s two Independents plus nine Republicans, voted for her.

President Obama commissioned Sotomayor on the day of her confirmation, and her swearing-in ceremony took place on August 8, 2009, at the Supreme Court Building. Chief Justice John Roberts administered the prescribed constitutional and judicial oaths of office, at which time she became the 111th justice (99th associate justice) of the Supreme Court. Sotomayor is the first Hispanic to serve on the Supreme Court, and is one of five women who have served on the Court, along with Sandra Day O’Connor (from 1981 to 2006), Ruth Bader Ginsburg (from 1993 to 2020), Elena Kagan (since 2010), and Amy Coney Barrett (since 2020). Sotomayor’s appointment gave the Court a record six Roman Catholic justices serving at the same time.

Sotomayor cast her first vote as an associate Supreme Court justice on August 17, 2009, in a stay of execution case. She was given a warm welcome onto the Court and was formally invested in a September 8 ceremony. Sotomayor’s inaugural case in which she heard arguments was on September 9 during a special session, Citizens United v. Federal Election Commission. It involved the controversial aspect of the First Amendment and the rights of corporations in campaign finance; Sotomayor dissented. In her vigorous examination of Floyd Abrams, representing the First Amendment issues in the case, Sotomayor challenged him, questioning 19th century rulings of the Court and saying, “What you are suggesting is that the courts, who created corporations as persons, gave birth to corporations as persons, and there could be an argument made that that was the Court’s error to start with … [imbuing] a creature of State law with human characteristics.”

In July 2010, Sotomayor signed a contract with Alfred A. Knopf to publish a memoir about the early part of her life. She received an advance of nearly $1.2 million for the work, which was published in January 2013 and titled My Beloved World (Mi mundo adorado in the simultaneously published Spanish edition). It focuses on her life up to 1992, with recollections of growing up in housing projects in New York and descriptions of the challenges she faced. It received good reviews, with Michiko Kakutani of The New York Times describing it as “a compelling and powerfully written memoir about identity and coming of age. … It’s an eloquent and affecting testament to the triumph of brains and hard work over circumstance, of a childhood dream realized through extraordinary will and dedication.” She staged a book tour to promote the work, and it debuted atop the New York Times Best Seller List.

In June 2010, the Bronxdale Houses development, where Sotomayor grew up, was renamed after her. The Justice Sonia Sotomayor Houses and Justice Sonia Sotomayor Community Center comprise 28 buildings with some 3,500 residents. While many New York housing developments are named after well-known people, this was only the second to be named after a former resident. In 2011, the Sonia M. Sotomayor Learning Academies, a public high school complex in Los Angeles, was named after her.

In 2011, Sotomayor wrote the majority opinion in J.D.B. v. North Carolina, in which the Supreme Court held that age is relevant when determining when a person is in police custody for Miranda purposes. J.D.B. was a 13-year-old student enrolled in special education classes whom police had suspected of committing two robberies. A police investigator visited J.D.B. at school, where he was interrogated by the investigator, a uniformed police officer, and school officials. J.D.B. subsequently confessed to his crimes and was convicted. J.D.B. was not given a Miranda warning during the interrogation, nor an opportunity to contact his legal guardian. In determining that a child’s age properly informs the Miranda custody analysis, Sotomayor wrote that “to hold… that a child’s age is never relevant to whether a suspect has been taken into custody— and thus to ignore the very real differences between children and adults— would be to deny children the full scope of the procedural safeguards that Miranda guarantees to adults”. Sotomayor’s opinion cited the Court’s earlier decisions in Stansbury v. California (holding that held that a child’s age “would have affected how a reasonable person” would “perceive his or her freedom to leave”) and Yarborough v. Alvarado (holding that a child’s age “generates commonsense conclusions about behavior and perception”). Sotomayor also pointed out that the law recognizes that child’s judgment is not the same as an adult’s, in the form of legal disqualifications on children as a class (e.g. limitations on a child’s ability to marry without parental consent). Associate Justice Samuel Alito, jointed by three other justices, wrote a dissenting opinion.

Sotomayor long lived in Greenwich Village in New York City and had few financial assets other than her home. She enjoys shopping, traveling, and giving gifts and helps support her mother and her mother’s husband in Florida. Regarding her short financial disclosure reports prior to her Supreme Court nomination, she has said, “When you don’t have money, it’s easy. There isn’t anything there to report.” As a federal judge, she is entitled to a pension equal to her full salary upon retirement. Upon joining the Supreme Court, she took up residence in Washington but sorely missed the faster-paced life of New York. After renting in the Cleveland Park neighborhood for three years, in 2012 she purchased a condominium in the U Street Corridor. She said, “I picked [that area] because it’s mixed. I walk out and I see all kinds of people, which is the environment I grew up in and the environment I love.”

There have been some deviations from the ideological pattern. In a 2013 book on the Roberts Court, author Marcia Coyle assessed Sotomayor’s position on the Confrontation Clause of the Sixth Amendment as a strong guarantee of the right of a defendant to confront his or her accusers. Sotomayor’s judicial philosophy on the issue is seen as being in parity with Elena Kagan and, unexpectedly for Sotomayor, also in at least partial agreement with the originalist reading of Antonin Scalia when applied to the clause.

By the end of her fifth year on the court, Sotomayor had become especially visible in oral arguments and in passionate dissents from various majority rulings, especially those involving issues of race, gender and ethnic identity. Sotomayor has shown her individuality on the Court in a number of decisions. In her reading of the constitutionality of the Obama health care law favoring the poor and disabled, she sided with Ginsburg against fellow liberals Breyer and Kagan. In dealing with the Chief Justice, Sotomayor had no difficulty in responding to his statement that “the way to stop discrimination on the basis of race is to stop discrimination on the basis of race,” by stating, “I don’t borrow Chief Justice Roberts’s description of what color-blindness is… Our society is too complex to use that kind of analysis.” In the manufacturer liability case of Williamson v. Mazda, which the court decided unanimously, she wrote a separate concurring opinion. Sotomayor’s rapport with her clerks is seen as more formalistic than some of the other justices as she requires detailed and rigorous evaluations of cases she is considering with a table of contents attached. When compared to Kagan directly, one of their colleagues stated, “Neither of them is a shrinking violet”. Coyle, in her 2013 book on the Roberts Court stated that: “Both women are more vocal during arguments than the justices whom they succeeded, and they have energized the moderate-liberal side of the bench.”

On December 31, 2013, Sotomayor pressed the ceremonial button and led the final 60-second countdown at the Times Square New Year’s Eve ball drop, being the first United States Supreme Court justice to perform the task.

In 2013, a painting featuring her, Sandra Day O’Connor, Ruth Bader Ginsburg, and Elena Kagan was unveiled at the Smithsonian’s National Portrait Gallery in Washington, D.C.

In 2014, Sotomayor dissented from a 6–3 ruling that granted Wheaton College of Illinois, a religiously affiliated university, an exemption from complying with Affordable Care Act (ACA)’s mandate on contraception. The ruling, which came the immediate wake of the Court’s 5–4 decision in Burwell v. Hobby Lobby, in which the conservative bloc had prevailed, was opposed by the court’s three female members: Sotomayor, Ginsburg and Kagan. Writing in dissent, Sotomayor wrote that the case was at odds with the majority’s previous statements in Hobby Lobby and said, “Those who are bound by our decisions usually believe they can take us at our word … Not today.” Sotomayor stated further her opinion that the decision compromised “hundreds of Wheaton’s employees and students of their legal entitlement to contraceptive coverage.”

In succeeding Justice Souter, Sotomayor had done little to change the philosophical and ideological balance of the Court. While many cases are decided unanimously or with different voting coalitions, Sotomayor has continued to be a reliable member of the liberal bloc of the court when the justices divide along the commonly perceived ideological lines. Specifically, her voting pattern and judicial philosophy has been in close agreement with that of Justices Breyer, Ginsburg and Kagan. During her first couple of years there, Sotomayor voted with Ginsburg and Breyer 90 percent of the time, one of the highest agreement rates on the Court. In a 2015 article titled “Ranking the Most Liberal Modern Supreme Court Justices”, Alex Greer identified Sotomayor as representing a more liberal voting pattern than both Elena Kagan and Ruth Bader Ginsburg. Greer placed Sotomayor as having the most liberal voting history of all the current sitting Justices, and slightly less liberal than her predecessors Thurgood Marshall and John Marshall Harlan II on the Court.

In May 2015 she received the Katharine Hepburn medal from Bryn Mawr College.

In January 2019, Bonnie Kristian of The Week wrote that an “unexpected civil libertarian alliance” was developing between Sotomayor and Neil Gorsuch “in defense of robust due process rights and skepticism of law enforcement overreach.”

In 2019, she was inducted into the National Women’s Hall of Fame.