Bitcoin stamped out.

• Author: Doherty, Brian
• Position: Currency crackdown - Brief article

MIKE CALDWELL was an early enthusiast for the digital currency Bitcoin. He started an online business called Casascius, which offered Bitcoin holders a physical token printed with the digital key for their holdings of the cryptocurrency. Mostly used as a memento or conversation-starter, Caldwell's tokens gave physical form to the ethereal conceptual currency.

These keepsakes might seem harmless. But to the federal government, which has become increasingly alarmed about the rise of online alternative currencies, turning digital money into a physical token could make you subject to a wide and far-reaching set of regulations.

In late November, Caldwell got a letter from the Financial Crimes Enforcement Network saying his business fell...