March 15 marks the 80th birthday of Justice Ruth Bader Ginsburg, the Thurgood Marshall of the campaign to establish equal legal rights for women. When Ginsburg entered Harvard Law School in 1956, laws governing women’s status were almost as discriminatory as the racial segregation laws that prevailed in the Southern states. The U.S. Supreme Court had previously held that women could constitutionally be barred from becoming lawyers, or from working in a bar unless their father or husband owned the establishment. Social Security laws, workers’ compensation laws and laws on determining pensions distinguished between male and female workers and were structured around the assumption that men worked and women stayed home and took care of the children. Thus it was unusual for a woman to work, and she could be paid less than a man since she really belonged at home. Other laws distinguished between men and women for purposes of jury service, promotion in the military, taxes and access to alcoholic beverages.

Ginsburg’s own life reflected the clear prejudice against women. There were only nine women in her Harvard Law School class of 500. The dean asked each woman why she was taking a seat meant for a man. She made law review after her first year, the traditional marker of high achievement in law school. She transferred her last year from Harvard to Columbia Law School when her husband, Martin Ginsburg, graduated from Harvard and began working in New York. She graduated in 1959 from Columbia at the top of her class.

But, despite her outstanding academic record, she could not get a job with a law firm. Although she was recommended for a Supreme Court clerkship with Justice Felix Frankfurter, he rejected her application on the grounds that the court was not ready for a female clerk. She did obtain a clerkship with a federal district court judge and then worked at Columbia Law School on a project about the Swedish legal system. In 1963, she began teaching at Rutgers Law School and later became a tenured professor at Columbia Law School.

In the meantime, Ginsburg set her goal of challenging the legal prejudices against women. She worked with the New Jersey office of the American Civil Liberties Union to tackle wage discrimination. The high point of her legal life, as she has described it, came in 1970, when a lawyer from Idaho asked for help from the ACLU in dealing with a state law that arbitrarily preferred a man over a woman in the appointment of an administrator for an estate. If an individual died without a will, leaving behind a brother and a sister, the law required the court to pick the brother over the sister, rather than appointing joint administrators (as it would if there were two brothers). There was no rhyme or reason to such a law. It was simply based on the assumption that men were more capable of dealing with financial matters than women. Ginsburg wrote the brief in that case, arguing that the equal-protection clause of the 14th Amendment did not permit states to discriminate against women. The Supreme Court found the law irrational in the case of Reed v. Reed, the first time the court invalidated a state law on sex-equality grounds.

With this opening wedge in place, Ginsburg founded the Women’s Rights Project at the ACLU and began to attack a variety of other laws that discriminated against women. Over the next decade, Ginsburg argued five sex-equality cases before the Supreme Court, winning four. She also submitted briefs in 11 other cases, all dealing with state or federal laws that applied different rules to men and women. All told, the court heard 19 cases alleging sex discrimination between 1971 and 1980, when Ginsburg was appointed to the federal bench. Virtually all of them bear her fingerprints as an advocate, a brilliant strategist and a tireless force for change. The legal principles that emerged from that decade of litigation changed the course of American women’s rights forever.

In 1994, Ginsburg was appointed to the U.S. Supreme Court (where she still sits). Just two years after her appointment, she authored the majority opinion in U.S. v. Virginia, in which the court struck down the male-only admissions policy of the Virginia Military Institute, a venerable public institution that prided itself on using a teaching technique — the "adversative model" — that it deemed unsuitable for female students. Ginsburg did not doubt that many women (and men) might find the "tormenting and punishing" aspects of a VMI education distasteful, but if even a small number would choose and qualify for admission, the state could not exclude all women as a class. The equal-protection clause, which she litigated to make meaningful for women, does not permit the government to deny to women, "simply because they are women, full citizenship stature — equal opportunity to aspire, achieve, participate in and contribute to society based on their individual talents and capacities." Indeed, the Department of Defense’s decision in January to lift all remaining barriers to women’s participation in military combat is a testament to the success of Ginsburg’s efforts, as advocate and then judge and then justice, to eradicate stereotypes about women’s ability and proper place in society.

In the past decade and a half, as the Supreme Court has shifted to the right, Ginsburg’s defense of women’s rights has been more often in dissent. She has argued that women who suffered pregnancy discrimination before it was illegal should not continue to be penalized as they reach retirement age and collect deflated pensions as a result of their leaves 40 years ago. She has argued for greater protection for unwed fathers — it was always part of her strategy as an advocate to bring discrimination against men into the discussion — when they seek to transmit citizenship to their children born abroad, something unwed mothers are able to do all but automatically.

And she wrote a powerful dissent to the court’s decision in Ledbetter v. Goodyear Tire & Rubber Co., which applied a stingy reading of Title VII in the pay-discrimination context that was insensitive, Gins­burg argued, to the "realities of the workplace." She implored Congress to correct the majority’s "parsimonious reading of Title VII," which it did with passage of the Lilly Ledbetter Fair Pay Act in 2009.

We commend Ginsburg for her innumerable contributions to women’s (and men’s) equality and wish her a very happy birthday.

Leon Friedman is the Joseph Kushner Distinguished Professor of Civil Liberties Law at Hofstra University Maurice A. Deane School of Law and the editor of Justices of the Supreme Court: Their Lives and Major Opinions (Facts on File 2013). Joanna L. Grossman is the Sidney and Walter Siben Distinguished Professor of Family Law at the law school and co-author of Inside the Castle: Law and the Family in 20th Century America (Princeton University Press 2011).