system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If it's illegal to deface US currency, what's with those penny squashers?
gpt
This is covered in 18 USC 331. It says that whoever *fraudulently* alters coins is guilty of a crime. The key word there is "fraudulently." If you alter a coin with the intent of defrauding somebody, you're guilty of a crime. If you alter or destroy a coin you own for reasons other than committing fraud, then you're just wasting money.

The origin of this statute goes back to the days when coins were made of precious metals, and their value was proportional to their metal content. In those days, you could shave some of the metal off a bunch of coins and melt it down to get an ingot that you could sell, while still passing the coins off as legal tender. The law exists to deter people from doing that. Today, coins have no intrinsic value so the practice of shaving them for their metal is extinct.