Professional attire can go a long way in communicating the level of respect you have for your occupation and the people around you. Lawyers don’t show up for court in shorts and politicians don’t often address crowds in sleeveless T-shirts.

So it stands to reason that the highest court in the country should have a dress code that reflects the gravity of their business, which is why most judges, including judges on the Supreme Court, are almost always bedecked in black robes. Why black?

As Reader's Digest reports, judges donning black robes is a tradition that goes back to judicial proceedings in European countries for centuries prior to the initial sitting of the U.S. Supreme Court in 1790. Despite that, there’s no record of whether the Justices went for a black ensemble. That wasn’t officially recorded until 1792—but the robes weren’t a totally solid color. From 1792 to 1800, the robes were black with red and white accents on the sleeves and in the front.

It is likely that Chief Justice John Marshall, who joined as the fourth chief justice of the Supreme Court in 1801, led the shift to a black robe—most likely because a robe without distinctive markings reinforces the idea that justice is blind. The all-black tradition soon spread to other federal judges.

But according to former Supreme Court Justice Sandra Day O’Connor, there is no written or official policy about the robes, and the Justices are free to source them however they like—typically from the same companies who outfit college graduates and choir singers. It’s certainly possible to break with tradition and arrive on the bench without one, as Justice Hugo Black did in 1969; Chief Justice William Rehnquist once added gold stripes to one of his sleeves. But for the most part, judges opt for basic black—a message that they’re ready to serve the law.

[h/t Reader’s Digest]