In some countries, judges wear colorful robes or other clothing, but U.S. judges almost always wear robes in black. This practice had its start in England, but its beginnings are not well understood. However, modern symbolic significance is a reason judges continue this tradition.
Black Robes in England
Judges in England traditionally wore robes of various colors. There is some debate over why they started wearing mainly black, but popular stories claim it began as a gesture of respect after the death of either Queen Anne in 1714 or Queen Mary II in 1694. In fact, black robes had already been the standard winter uniform for judges since 1635, and colorful robes continued to be worn long after 1714.
The U.S. inherited the tradition of robes for judges, but there has never been a formal rule saying they have to wear black. Early Supreme Court justices sometimes dressed in red or other colors. However, in 1801, incoming Chief Justice John Marshall made a habit of wearing a plain black robe for the sake of simplicity, and the tradition stuck.
Today, wearing nearly identical black robes is a way of showing that all the country’s judges are united in the same responsibility to uphold the law. The simplicity of their attire can also symbolize the judges' neutrality and humility as servants of the people, though to some the robes instead represent prestige, government power and authority.