Frankfurter was born into a Jewish family on November 15, 1882, in Vienna, Austria, then part of the Austro - Hungarian Empire in Europe. He was the third of six children of Leopold and Emma (Winter) Frankfurter. His forebears had been rabbis for generations. In 1894, when he was twelve, his family immigrated to the United States, where he learned English growing up on New York City's Lower East Side. Frankfurter attended P.S. 25 where he excelled at his studies and enjoyed chess and crap shooting on the street. He spent many hours reading at The Cooper Union as well as attending political lectures, usually on subjects such as trade unionism, socialism, and communism.

After graduating from City College of New York (where he was inducted into Phi Beta Kappa) in 1902, Frankfurter worked for the Tenement House Department of New York City in order to raise money for law school. He applied successfully to Harvard Law School, where he excelled academically and socially. He became lifelong friends with Walter Lippmann and Horace Kallen, became an editor of the Harvard Law Review, and graduated with one of the best academic records since Louis Brandeis.

Frankfurter's legal career began when he joined the New York law firm of Hornblower, Byrne, Miller & Potter in 1906. In the same year he became the assistant of Henry Stimson, the US attorney for the Southern District of New York. During this period, Frankfurter read Herbert Croly's book The Promise of American Life, and became a supporter of New Nationalism and Theodore Roosevelt. In 1911, President William Howard Taft appointed Stimson as his Secretary of War, and Stimson appointed Frankfurter as law officer of the Bureau of Insular Affairs, though Frankfurter in fact worked as Stimson's assistant and confidant. His government position restricted his ability to publicly voice his Progressive views, though he expressed his opinions clearly in private to friends such as Judge Learned Hand. In 1912 Frankfurter supported the Bull Moose campaign to return Roosevelt to the presidency and was bitterly disappointed when Woodrow Wilson was elected. He became increasingly disillusioned with the established parties, and described himself as "politically homeless".

When the United States entered World War I in 1917 Frankfurter took a special leave from Harvard to serve as special assistant to the Secretary of War Newton D. Baker. He was appointed Judge Advocate General, supervising military courts - martial for the War Department. In September 1917, he was appointed counsel to a commission established by President Wilson to resolve major strikes threatening war production, the President's Mediation Committee. Among the disturbances he investigated were the 1916 Preparedness Day Bombing in San Francisco, where he argued strongly that the radical leader Thomas Mooney had been framed and required a new trial. He also examined the copper industry in Arizona, where industry bosses solved industrial relations problems by having more than 1,000 strikers forcibly deported to New Mexico. Overall, Frankfurter's work gave him an opportunity to learn first hand about labor politics and extremism, including anarchism, communism and revolutionary socialism. He came to sympathize with labor issues, arguing that "unsatisfactory, remediable social conditions, if unattended, give rise to radical movements far transcending the original impulse." His activities led the public to view him as a radical lawyer and supporter of radical principles, and he was accused by former President Theodore Roosevelt of being "engaged in excusing men precisely like the Bolsheviki in Russia."

As the war drew to a close, Frankfurter was among the nearly one hundred intellectuals who signed a statement of principles for the formation of the League of Free Nations Associations, which aimed to increase American participation in international affairs.

Frankfurter was encouraged by Supreme Court Justice Louis Brandeis to become more involved in Zionism. With Brandeis he lobbied President Wilson to support the Balfour Declaration, a British government statement supporting the establishment of a Jewish homeland in Palestine. In 1918, he participated in the founding conference of the American Jewish Congress in Philadelphia creating a national democratic organization of Jewish leaders from all over the US. In 1919, Frankfurter served as a Zionist delegate to the Paris Peace Conference.

In 1919, Frankfurter married Marion Denman, the daughter of a Congregational minister and a Smith College graduate. They married after a long and difficult courtship, and against the wishes of his mother, who was disturbed by the prospect of her son marrying outside the Jewish faith. Frankfurter himself was a non-practicing Jew, and regarded religion as "an accident of birth". Frankfurter was a dominating husband and Denman suffered from frail health, which resulted in frequent mental breakdowns. The couple had no children.

Frankfurter's activities continued to attract attention for their alleged radicalism. In November 1919, he chaired a meeting in support of American recognition of the newly created Soviet Union. In 1920, Frankfurter helped to found the American Civil Liberties Union. Following the arrest of suspected communist radicals in 1919 and 1920 during the Palmer raids, Frankfurter, together with other prominent lawyers including Zechariah Chafee, signed an ACLU report which condemned the "utterly illegal acts committed by those charged with the highest duty of enforcing the laws" including entrapment, police brutality, prolonged incommunicado detention, and violations of due process in court. Frankfurter and Chafee also submitted briefs to a habeas corpus application to the Massachusetts Federal District Court. Judge George Anderson ordered the discharge of twenty aliens, and his denunciation of the raids effectively ended them.

In 1921, Frankfurter was given a chair at Harvard Law School, and continued progressive work on behalf of socialists and oppressed and religious minorities. When A. Lawrence Lowell, the President of Harvard University, proposed to limit the enrollment of Jewish students, Frankfurter worked with others to defeat the plan.

In the late 1920s, he came to public attention when he supported calls for a new trial for Sacco and Vanzetti, two Italian immigrant anarchists who had been sentenced to death on robbery and murder charges. Frankfurter wrote an influential article for the Atlantic Monthly and subsequently a book, The Case of Sacco and Vanzetti: A Critical Analysis for Lawyers and Laymen. He critiqued the prosecution's case and the judge's handling of the trial and asserted that the convictions were the result of anti - immigrant prejudice and enduring anti - radical hysteria of the Red Scare of 1919 – 20. His actions further isolated him from his Harvard colleagues and from Boston society.

Following the election of Franklin D. Roosevelt in 1932, Frankfurter quickly became a trusted and loyal adviser to the new president. He was among the most conservative of Roosevelt's advisers, arguing against the extreme economic plans of Raymond Moley, Adolf Berle and Rex Tugwell, while clearly recognizing the need for major changes to deal with the inequalities of wealth distribution that had led to the devastating nature of the Depression. Frankfurter successfully recommended many bright young lawyers toward public service with the New Deal administration, so many indeed that they became known as "Felix's Happy Hot Dogs". Among the most notable of these were Thomas Corcoran and Benjamin Cohen. He moved to Washington, DC, commuting back to Harvard for classes, but as with previous experiences, was never fully accepted within government circles. He worked closely with Louis Brandeis, lobbying for political activities suggested by Brandeis. He declined a seat on the Supreme Judicial Court of Massachusetts and, in 1933, the position of Solicitor General of the United States. Long an anglophile, Frankfurter had studied in Oxford in 1920, and in 1933 - 4 he returned to act as visiting Eastman professor in the faculty of Law.

Following the death of Supreme Court Justice Benjamin N. Cardozo in July 1938, President Franklin D. Roosevelt asked his old friend Frankfurter for recommendations of prospective candidates for the vacancy. Finding none on the list to suit his criteria, Roosevelt nominated Frankfurter himself, and he was confirmed without dissent. The Senate confirmation hearing on the nomination of Frankfurter is notable for being the first time that a nominee for the Supreme Court appeared in person before the Judiciary Committee. He served from January 30, 1939 to August 28, 1962. He wrote 247 opinions for the Court, 132 concurring opinions, and 251 dissents.

Frankfurter became the court's most outspoken advocate of judicial restraint, the view that courts should not interpret the fundamental law, the constitution, in such a way as to impose sharp limits upon the authority of the legislative and executive branches. He also usually refused to apply the federal Constitution to the states. In the case of Irvin v. Dowd, Frankfurter would state what was for him a frequent theme: "The federal judiciary has no power to sit in judgment upon a determination of a state court... Something that thus goes to the very structure of our federal system in its distribution of power between the United States and the state is not a mere bit of red tape to be cut, on the assumption that this Court has general discretion to see justice done...".

In his judicial restraint philosophy, Frankfurter was heavily influenced by his close friend and mentor Oliver Wendell Holmes, Jr., who had taken a firm stand during his tenure on the bench against the doctrine of "economic due process". Frankfurter revered Justice Holmes, often citing Holmes in his opinions. In practice, this meant Frankfurter was generally willing to uphold the actions of those branches against constitutional challenges so long as they did not "shock the conscience." Frankfurter was particularly well known as a scholar of civil procedure.

Frankfurter's adherence to the judicial restraint philosophy was shown in the 1940 opinion he wrote for the court in Minersville School District v. Gobitis, a case involving Jehovah's Witnesses students who had been expelled from school due to their refusal to salute the flag and recite the Pledge of Allegiance. He rejected claims that First Amendment rights should be protected by law, and urged deference to the decisions of the elected school board officials. He stated that religious belief "does not relieve the citizen from the discharge of political responsibilities" and that exempting the children from the flag saluting ceremony "might cast doubts in the minds of other children" and reduce their loyalty to the nation. Judge Harlan Fiske Stone issued a lone dissent. The court's decision sparked hundreds of violent attacks on Jehovah's Witnesses throughout the country, and was subsequently overturned in March 1943 by the Supreme Court decision on West Virginia Board of Education v. Barnette. Former ally, Supreme Court justice Robert H. Jackson wrote the majority opinion in this case, which also concerned Jehovah's Witnesses students expelled from school for refusing to salute the flag. Jackson's opinion, which contradicted Frankfurter's on most points, elicited an impassioned dissent from Frankfurter. In it he rejected the notion that as a Jew he ought "to particularly protect minorities." He reiterated his view that the role of the Court was not to give an opinion of the "wisdom or evil of a law" but only to determine "whether legislators could in reason have enacted such a law".

In the apportionment case of Baker v. Carr, Frankfurter's position was that the federal courts did not have the right to tell sovereign state governments how to apportion their legislatures; he thought the Supreme Court should not get involved in political questions, whether federal or local. Frankfurter's view had won out in the 1946 case preceding Baker, Colegrove v. Green – there, a 4–3 majority decided that the case was non - justiciable, and the federal courts had no right to become involved in state politics, no matter how unequal district populations had become. However, the Baker case would settle the matter – the drawing of state legislative districts was within the purview of federal judges, despite Frankfurter's warnings that the Court should avoid entering "the political thicket."

Frankfurter reaffirmed this view in a concurring opinion written for the 1951 Dennis v. United States Supreme Court ruling. The decision affirmed, by a 6–2 margin, the conviction of eleven communist leaders for conspiring to overthrow the US government under the Smith Act. In it, he once again argued that judges "are not legislators, that direct policy - making is not our province." He also recognized that curtailing the free speech of those who advocate the overthrow of government by force, also risked stifling criticism by those who did not, writing that "[it] is a sobering fact that in sustaining the convictions before us we can hardly escape restriction on the interchange of ideas."

A pivotal school desegregation case came before the court in Brown v. Board of Education. It was argued, and was set for reargument when Chief Justice Fred M. Vinson died. It has been reported that Frankfurter remarked that Vinson's death was the first solid piece of evidence he had seen to prove the existence of God. It should be noted that this story was tied to a scheduled reargument in which Vinson's vote could be crucial (in Brown vs. Board of Education, where ostensibly Vinson was not disposed to overrule Plessy vs. Ferguson), and in any event, some believe the story to be "possibly apocryphal."

Frankfurter demanded that the opinion in 1955's Brown v. Board of Education II order desegregation with the phrase of "all deliberate speed". The phrase gave school boards across the country an excuse to defy the demands of the first Brown decision. For fifteen years, schools in the South remained segregated, until the Supreme Court's opinion in Alexander v. Holmes County Board of Education. There, the Court would write that "The obligation of every school district is to terminate dual school systems at once and to operate now and hereafter only unitary schools."

Frankfurter was hands-off in the area of business. In the 1956 government case against DuPont, started because DuPont seemed to have maneuvered its way into a preferential relationship with GM, Frankfurter refused to find a conspiracy, and said the Court had no right to interfere with the progress of business. Here again, Frankfurter opposed the views of Justices Warren, Black, Douglas, and Brennan (though Frankfurter lost 4–3).

Later in his career, Frankfurter's judicial restraint philosophy frequently put him on the dissenting side of ground breaking decisions taken by the Warren Court to end discrimination.

Frankfurter believed that the authority of the Supreme Court would be reduced if it went too strongly against public opinion: He sometimes went to great lengths to avoid unpopular decisions, including fighting to delay court decisions against racial intermarriage.

For the October 1948 Supreme Court Term, Frankfurter hired William Thaddeus Coleman as a law clerk, the first African American to serve as a Supreme Court law clerk.

Throughout his career on the court, Frankfurter was a large influence on many justices, such as Clark, Burton, Whittaker, and Minton. He generally attempted to influence any new justice coming in, though he managed to repel Justice Brennan – who had voted with Frankfurter half the time in his first year, but then opposed him after Frankfurter's attempts at inculcation. Frankfurter turned against Brennan completely after the case of Irvin v. Dowd. Other justices who received the Frankfurter treatment of flattery and instruction were Burton, Vinson, and Harlan. With Vinson, who became Chief Justice, Frankfurter feigned deference, though he sought influence.

Justice Frankfurter was in his time the leader of the conservative faction of the Supreme Court; he would for many years feud with liberals like Justices Black and Douglas. He often complained that they "started with a result" and that their work was "shoddy," "result - oriented," and "demagogic". Similarly, Frankfurter panned the work of Chief Justice Earl Warren as "dishonest nonsense."

Frankfurter saw justices with ideas different from his own as part of a more liberal "Axis" – these opponents were chiefly Justices Black and Douglas, but would also include Murphy and Rutledge; the group would for years oppose Frankfurter's judicially restrained ideology. Douglas, Murphy, and then Rutledge were the first justices to agree with Hugo Black's notion that the Fourteenth Amendment incorporated the Bill of Rights protection into it; this view would later mostly become law, during the period of the Warren Court. For his part, Frankfurter would assert that Black's incorporation theory would usurp state control over criminal justice by limiting states' development of new interpretations of criminal due process.

Frankfurter's argumentative style was not popular among his Supreme Court colleagues. "All Frankfurter does is talk, talk, talk," Chief Justice Earl Warren complained. "He drives you crazy." Hugo Black reported that "I thought Felix was going to hit me today, he got so mad." In the Court's biweekly conference sessions, traditionally a period for vote counting, Frankfurter had the habit of lecturing his colleagues for forty-five minutes at a time or more with his book resting on a podium. Frankfurter's ideological opponents would leave the room or read their mail while he lectured.

Frankfurter was close friends with Justice Robert H. Jackson. The two exchanged much correspondence over their mutual dislike for Justice William O. Douglas. Frankfurter also had a strong influence over Jackson's opinions.

Frankfurter was universally praised for his work before coming to the Supreme Court, and was expected to influence it for decades past the death of FDR. However, Frankfurter's influence over justices was limited by his failure to adapt to new surroundings, his style of personal relations (relying heavily on the use of flattery and ingratiation, which ultimately proved divisive), and his strict adherence to the ideology of judicial restraint. Michael E. Parrish, professor at UCSD, said of Frankfurter: "History has not been kind to [him]... there is now almost a universal consensus that Frankfurter the justice was a failure, a judge who... became 'uncoupled from the locomotive of history' during the Second World War, and who thereafter left little in the way of an enduring jurisprudential legacy."

Frankfurter published several books including Cases Under the Interstate Commerce Act; The Business of the Supreme Court (1927); Justice Holmes and the Supreme Court (1938); The Case of Sacco and Vanzetti (1927) and Felix Frankfurter Reminisces (1960).

Frankfurter retired in 1962 after suffering a stroke and was succeeded by Arthur Goldberg. He was awarded the Presidential Medal of Freedom in 1963.

During World War II Frankfurter was presented with a historic opportunity to pursue a mission in the service of humanity. In 1943, Jan Karski, an officer in the Polish underground, traveled to Washington as an emissary of the resistance to meet with Franklin Roosevelt and report to the President on the European conflict and specifically conditions in his own country, Poland. Roosevelt requested that Karski meet with Justice Frankfurter, as it would be of vital concern for Frankfurter, himself a Jew, to be apprised of the horrors befalling his fellow Jews in Poland. Frankfurter listened to Karski’s detailed accounts of the program of extermination of the Jewish people carried out by the Nazis. Karski provided his own eyewitness accounts of the liquidation of the Warsaw Ghetto and Belzec concentration camp. Karski’s testimony of this conference with Frankfurter was recorded in an interview for the documentary film produced in 1978, by Claude Lanzmann ("Shoah"), titled "The Karski Report.” “Karski reproduces, for Lanzmann's camera with a theatrical fervor that embodies the shock he felt upon hearing” Frankfurter render his verdict on the atrocities he had just heard. “I do not believe you.” The oral testimony provided by Karksi addresses the moral challenge presented Frankfurter and the human inability to "conceive the unconceivable and to recognize what Karski calls ' the unprecedented.' "

Felix Frankfurter died from congestive heart failure at the age of 82. His remains are interred in the Mount Auburn Cemetery in Cambridge, Massachusetts.

There are two extensive collections of Frankfurter's papers: one at the Manuscript Division of the Library of Congress and the other at Harvard University. Both are fully open for research and have been distributed to other libraries on microfilm. A chapter of the international youth led fraternal organization for Jewish teenagers Aleph Zadik Aleph in Scottsdale, AZ is named in his honor.