Reply #63: FDR did it in the early 30s.

[girl gone mad]

He demonetized gold, and people were told to turn in their coins for face value (not long after, the redemption price was nearly doubled). I don't believe anyone was ever prosecuted for refusing to turn in their gold, and many people sent their gold to foreign banks.

Technically, the government can seize just about any of your assets for cash if it wants. Considering how many gun nuts hoard gold, I have a hard time imagining the scenario in which precious metals get seized.

If you're concerned, you can get some protection by buying foreign coins with a face value closer to that of the going rate.