She began her career as a professor at the University of Chicago Law School, leaving to serve as Associate White House Counsel, and later as a policy adviser under President Bill Clinton.

[6] The following year, President Obama nominated her to the Supreme Court to fill the vacancy arising from the impending retirement of Justice John Paul Stevens.

[14] She was independent and strong-willed in her youth and, according to a former law partner of her father's, clashed with her Orthodox rabbi, Shlomo Riskin, over aspects of her bat mitzvah.

As part of her graduation requirement, Kagan wrote a thesis called "The Development and Erosion of the American Exclusionary Rule: A Study in Judicial Method".

[34] Marshall said he hired Kagan to help him put the "spark" back into his opinions as the Court had been undergoing a conservative shift since William Rehnquist became Chief Justice in 1986.

[41][42] While on the faculty there, Kagan published a law review article on the regulation of First Amendment hate speech in the wake of the Supreme Court's ruling in R.A.V.

[49] Kagan coauthored a 1997 memo urging Clinton to support a ban on late-term abortions: "We recommend that you endorse the Daschle amendment in order to sustain your credibility on HR 1122 and prevent Congress from overriding your veto.

"[50] On June 17, 1999, Clinton nominated Kagan to the U.S. Court of Appeals for the District of Columbia Circuit, to replace James L. Buckley, who took senior status in 1996.

She initially sought to return to the University of Chicago, but she had given up her tenured position during her extended stint in the Clinton Administration, and the school chose not to rehire her, reportedly due to doubts about her commitment to academia.

According to Campus Progress, As dean, Kagan supported a lawsuit intended to overturn the Solomon Amendment so military recruiters might be banned from the grounds of schools like Harvard.

The case was challenged in the Supreme Court, which ruled the military could indeed require schools to allow recruiters if they wanted to receive federal money.

[72] The two main questions senators had for Kagan during her confirmation hearings were whether she would defend statutes that she personally opposed and whether she was qualified to be Solicitor General given her lack of courtroom experience.

[73] As Solicitor General, Kagan's job was to act as the lawyer for the United States and defend legislation and executive actions in appeals before the Supreme Court.

[76] Kagan's first appearance before the Supreme Court was on September 9, 2009, one month before the typical start of a new term in October, in the re-argument of Citizens United v. Federal Election Commission, 558 U.S. 310 (2010).

[76] She helped win four cases: Salazar v. Buono, 559 U.S. 700 (2010), United States v. Comstock, 560 U.S. 126 (2010), Holder v. Humanitarian Law Project, 561 U.S. 1 (2010), and Free Enterprise Fund v. Public Company Accounting Oversight Board, 561 U.S. 477 (2010).

[88] On April 9, 2010, Justice John Paul Stevens announced he would retire at the start of the Court's summer 2010 recess, triggering new speculation about potential replacements, and Kagan was once again considered a contender.

[89] In a Fresh Dialogues interview, Jeffrey Toobin, a Supreme Court analyst and Kagan's friend and law school classmate,[90] speculated that she would be Obama's nominee, describing her as "very much an Obama-type person, a moderate Democrat, a consensus builder".

[97] Like many prior nominees, including Chief Justice John Roberts, she declined to answer whether she thought particular cases were correctly decided or how she would vote on particular issues.

[101] The voting was largely along party lines, with five Republicans (Richard Lugar, Judd Gregg, Lindsey Graham, Susan Collins, and Olympia Snowe) supporting her and one Democrat (Ben Nelson) opposing.

[118] Unlike Marsh v. Chambers, 463 U.S. 783 (1983), in which the Supreme Court allowed a state legislature to open with a prayer, Kagan noted the board in Greece was a forum for ordinary citizens.

Kagan agreed with Kennedy that the Court's decision created inequity and drew an arbitrary distinction, but further opined that Monsanto might have been wrongly decided.

[120][122][121] Her vote thus rested on procedural grounds as she expressed skepticism that the government should be able to freeze the assets of a criminal defendant not yet convicted, and thus still benefiting from the presumption of innocence, by merely showing probable cause that the property will be subject to forfeiture.

[124][125][126] In a footnote, Kagan set forth a new principle, that congressional districts drawn with race as the dominant factor may be found to be an unlawful racial gerrymander even if they have another goal, such as sorting voters by political affiliation.

She concluded, "The law that confronted one of this country’s most enduring wrongs; pledged to give every American, of every race, an equal chance to participate in our democracy; and now stands as the crucial tool to achieve that goal.

"[128] Joined by Justices Breyer and Sotomayor, Kagan dissented in West Virginia v. EPA, which struck down the proposed Clean Power Plan.

[139] [140][141][142] She voted with the liberal bloc in King v. Burwell, 576 U.S. 988 (2015), finding that Obamacare's subsidies and individual mandate are constitutional, and in Obergefell v. Hodges, 576 U.S. 644 (2015), which prohibits states from banning same-sex marriage.

[143] In 2018, Slate observed that Kagan had crossed ideological lines on multiple cases during the preceding term, and considered her part of a centrist bloc, along with Roberts, Stephen Breyer, and Anthony Kennedy.

It includes Alaska, Arizona, California, Guam, Hawaii, Idaho, Oregon, Montana, Nevada, the Northern Mariana Islands, and Washington state.

Former Supreme Court Justice Sandra Day O'Connor wrote the article on Kagan, calling her "an incisive legal thinker" and "excellent communicator".

[160] Kagan is known to spend time with longtime friends from law school and from her stint in the Clinton administration rather than attending Washington, D.C. social events she is invited to as a justice.