Lady Justice, a blindfolded woman carrying a sword and a set of scales, is a common symbol on courthouses in America and inside some court rooms. She symbolizes fair and equal administration of the law, without corruption, favor, greed, or prejudice.
"Lady Justice originates from the personification of Justice in Ancient Roman art known as Iustitia or Justitia after Latin: Iustitia, who is equivalent to the Greek goddesses Themis and Dike."
The blindfold represents objectivity and impartiality, that justice should be meted out without fear or favor, regardless of money, wealth, or power.
She holds scales to represent the weighing of evidence, evidence must be weighed on its own merit.
The sword represents punishment, signifying that justice can be swift and final. She holds the sword below the scales to show that evidence weighted on its merit in a court of law come before punishment.
The snake under her foot represents evil, and lies, and the book is the law, the constitution from which justice is administered.