Judge Clay was once a corrupt Gotham City judge who murdered a criminal that had dirt on him. During the investigation of the murder, Clay's daughter Melissa Clay was attacked by a criminal that was startled by Batman. The criminal fired a rifle which grazed her forehead and caused her to go blind resulting in Clay deciding to enact vengeance on the Dark Knight.
Several years later, Clay resurfaced under the alias of "The Judge" and kidnapped Robin to try and lure Batman into a series of death-traps. When Melissa tried to speak sense to her father, he refused to listen which only caused her to blindly wander into one of her father's death-traps, killing her. After this, Clay became horrified with his actions and willingly handed himself over the authorities.
Following this, Judge Clay's mallet was put on display by Batman in the Batcave.