With its rigorous postgraduate education, grueling exams and highly competitive job market, law is one of the hardest professions to enter.

But the process wasn’t always so complex. In fact, the early lawyers and judges of the United States of America didn’t go to law school, and 57%—64 out of all 112—Supreme Court Justices of the United States never got their Juris Doctorate degree.

How is that possible?

In lieu of going to law school—which was uncommon in the U.S. until the late 1800’s—20 justices simply studied law under a current judge or lawyer. Forty-four others attended law school, but never graduated, pursuing a scholarly education outside of their universities instead.

The first justice to attend, but not graduate from law school, was John Blair Jr. in 1756, and the last was Robert Houghwout Jackson in 1912.

It wasn’t until 1832, when Benjamin Robbins graduated from Harvard University, that the first justice-to-be obtained a Juris Doctorate degree.

But even then, justices continued to enter the Supreme Court without a J.D. until 1941, when the last two men without the degree—James Frances Byrnes (never attended law school) and Robert Houghwout Jackson (attended Albany Law School, but never graduated)—entered the court.

In all, 48 Supreme Court Justices of the United States successfully graduated from law school. The ones that produced the most justices are Harvard (15), Yale (6), and Columbia (2).

Every member of today’s Supreme Court got their J.D. from one of the top three most common schools.

Five went to Harvard (John G. Roberts Jr., Atonin Scalia, Athony M. Kennedy, Stephen G. Breyer, and Elena Kagan), three went to Yale (Clarence Thomas, Samuel A. Alito Jr., and Sonia M. Sotomayor), and one went to Columbia (Ruth Bader Ginsburg).

This article was written for TIME by Kiran Dhillon of FindTheBest.

Contact us at letters@time.com.