UPDATED 11:41 p.m.

The United States Senate has confirmed former Harvard Law School Dean Elena Kagan as an associate justice of the Supreme Court, making her the first former dean to join the nation's highest judicial body.

By a 63-37 vote, the Senate approved Kagan as the third woman to join the current Court—the highest number of women to have ever served at one time.

Thursday's confirmation came largely along party lines, with the group in favor of Kagan's confirmation featuring a stronghold of 56 Democrats, two independents, and five Republicans. The opposing side was composed of 36 Republicans and one Democrat.

Kagan's ascension to the Court comes after at times tense confirmation hearings that heavily featured her tenure as dean—particularly her stance on military recruiting at the Law School.

During the hearings, Kagan was consistently challenged by many Senate Republicans for her treatment of the military as dean. She had temporarily banned the military from using the Law School’s Office of Career Services facilities, arguing that the "Don’t Ask, Don’t Tell" policy—which openly bans those who are openly gay, lesbian, or bisexual from serving in the military—did not align with the school’s non-discrimination policy.

Senator Jeff Sessions, the Alabama Republican, claimed that Kagan had treated the military in a "second-class way" as dean. In response, Kagan said that she had worked to both uphold the University's anti-discrimination policy and ensure that the military would have access to Law School students.

Kagan, who will be the first Justice since William H. Rehnquist without prior judicial experience, was also criticized in the hearings for her lack of formal judicial background. At 50, she is now the youngest Justice on the Court.

Kagan most recently served as Solicitor General, playing an integral role in guiding Barack Obama administration's interaction with the Supreme Court. Last January, she announced that she would resign the deanship at the Law School—a position she had held since 2003—in light of her nomination for the government post.

In May, Kagan was nominated by Obama to replace Justice John Paul Stevens on the Supreme Court. In the days leading up to Kagan's confirmation hearings, which commenced on June 28, colleagues publicized their support for the candidate.

In a letter to two members of the Senate Judiciary Committee, more than 60 deans at major American law schools—including current Harvard Law School Dean Martha L. Minow—expressed their suport for Kagan's nomination. In yet another letter, eight solicitors general stated their belief that Kagan would "serve on the Court with distinction."

Law School Professor Lawrence Lessig said that it was "wonderful" that Kagan was confirmed in a relatively quick decision, despite the fact that the Massachusetts senators could not come to a unanimous decision in support of Kagan.

—Staff writer Elias J. Groll can be reached at egroll@fas.harvard.edu.

—Xi Yu contributed to the reporting of this story.