ATM PIN reversal is a system designed to alert police that a forced withdrawal is in progress when a user inputs his PIN in reverse. As of 2014, the system is not used in any ATMs.
The system was patented by Joseph Zingher in 1998. He tried to interest the banking community but had no success. Banks have not been interested because of the cost to implement the system and doubts about its effectiveness. Bills have been submitted in multiple states to make the system mandatory, but as of 2014, none have been successful. A chain letter email hoax that began in 2006 stated that the system was in place at all ATMs.