A smart idea from the Halfbakery:
In addition to the regular PIN number (*), each bank card would have a second PIN number that would indicate the user was in some sort of distress (such as being forced to withdraw money at gunpoint). Use of this alternate PIN would summon the police and perhaps put the ATM’s camera in a higher resolution and/or frame rate mode. The panic PIN would otherwise function just like the regular PIN in that money could be gotten from the machine, so that the hostile party would not be able to tell that authorities had been called. Perhaps the ATM could distribute marked bills as well.
I think that the general knowledge that any coerced PIN or transaction could actually be used to summon the police would dramatically lower the incindence of crimes against ATM users.
(*) Yes, I know that “PIN number” is redundant.
Credit: Danville Police
I really like this idea but I worry that most people wouldn’t remember the “panic PIN” – especially in such a stressful situation. I know a lot of people who hardly know their normal, frequently used code. But maybe the fact that one could alert the police is enough determent to lower the incindence of crimes against ATM users.

