Lady Justice is a common sight on courthouses and legal institutions. There is regional variation on her precise depiction, though certain fundamentals are constant: She carries a sword, scales for weighing, and usually (though not always) wears a blindfold. She is garbed in a Greco-Roman toga or tunica, in the tradition of classical goddesses, philosophers and prophets. Images of her can be found across the world.
The concept of a goddess of justice is old indeed, dating to ancient Egyptian and Greek times. The Egyptians had Ma'at, who stood for order and carried both a sword and the Feather of Truth. The Greeks had the goddess Themis, who stood for law, order and justice (and who, incidentally, was mother to the Fates, who themselves were noted for judging humanity).
The Roman goddess of justice, Justitia, is the most direct inspiration, since she carried the sword, scales and blindfold we are familiar with today.
The scales date back to Egyptian times, where the god Anubis was invariably depicted with a set of scales to weigh a deceased person's soul against the Feather of Truth. The modern interpretation filters through the Enlightenment's focus on reason, as Lady Justice weighs the factors of a case to render a verdict. The scales imply a mechanistic, rational process; too much weight (evidence) on one side will cause the scales to tilt in favor of innocence or guilt.
Lady Justice often carries a sword in one hand. The sword is a historical symbol of authority, wielded by kings, emperors and generals. It is therefore one of the earliest symbols for justice, as the power of a monarch could be delivered with a stroke of the sword. Additionally, the sword has an esteemed place in ceremony even today, as people who are knighted are touched upon the shoulders with a blade. Lady Justice's sword advances the concept that justice can be swift and final.
The blindfold she wears symbolizes the philosophy that justice should be rendered "without passion or prejudice." Considering only the facts on her scale, Lady Justice does not bother with letting emotional impressions of the accused enter into the implicit equation. All are fair before the facts of the case and the judgment of Justice. Not all depictions of Lady Justice feature the blindfold, however.
Lady Justice wears the garments of classic Greece and Rome. This owes to her origins as an interpretation of Justitia. It also serves to underscore the place of the toga in western tradition; such garments represented civilization and philosophy. A popular expression in ancient Rome was: "Cedant arma togae," which means "Let arms (war) give way to the toga (civil power)."