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I assume they would fingerprint every note at manufacture, then compare every note at purchase time to see if it matches a known good fingerprint. You would nee

I assume they would fingerprint every note at manufacture, then compare every note at purchase time to see if it matches a known good fingerprint. You would need to completely remake all bills in circulation with a new style and make invalid the old style, and equip everyone that takes cash with a fingerprint machine. If they tried to just slowly scan in existing bills people would just keep making the fakes, I would imagine.

mannykannot 6y ago
You do not have to equip everyone who takes cash with a scanner, as banknotes regularly circulate through banks. I do not know how, and how frequently, current anti-counterfeiting measures are checked, but the more subtle of them are almost never checked in ordinary cash transactions. Presumably they are checked somewhere?
- thatguy0900 6y ago
  I would imagine the only time it is important to stop a counterfeit bill is the first time its used, right? If the goal is to stop people from counterfeiting, at least.
  - mannykannot 6y ago
    I don't think that has ever been realistic. Like credit-card fraud, check kiting and other petty crimes, it is only realistic to stop it growing to the point of being a widespread problem that threatens the economic infrastructure.
UncleEntity 6y ago
> You would need to completely remake all bills in circulation with a new style and make invalid the old style... It takes a while for all the old bills to get out of circulation though -- a few years ago I got my hands on a $20 bill from 1970 and the kid at the corner store almost didn't take it since they had apparently never seen one that old, probably didn't help it was nice and crisp as well. Only thing I can imagine is someone was saving it from their birth year and had to spend it for whatever reason since $20 in 1970 was over $100 in today's dollars so they lost a bunch of value holding that bill.

mannykannot 6y ago

You do not have to equip everyone who takes cash with a scanner, as banknotes regularly circulate through banks. I do not know how, and how frequently, current anti-counterfeiting measures are checked, but the more subtle of them are almost never checked in ordinary cash transactions. Presumably they are checked somewhere?

thatguy0900 6y ago
I would imagine the only time it is important to stop a counterfeit bill is the first time its used, right? If the goal is to stop people from counterfeiting, at least.
- mannykannot 6y ago
  I don't think that has ever been realistic. Like credit-card fraud, check kiting and other petty crimes, it is only realistic to stop it growing to the point of being a widespread problem that threatens the economic infrastructure.

UncleEntity 6y ago

> You would need to completely remake all bills in circulation with a new style and make invalid the old style... It takes a while for all the old bills to get out of circulation though -- a few years ago I got my hands on a $20 bill from 1970 and the kid at the corner store almost didn't take it since they had apparently never seen one that old, probably didn't help it was nice and crisp as well. Only thing I can imagine is someone was saving it from their birth year and had to spend it for whatever reason since $20 in 1970 was over $100 in today's dollars so they lost a bunch of value holding that bill.