Although the use of cash continues to decline in both the legitimate and illicit economies, lots of criminal transactions, including bribe payments, still use cash—slipped into pockets or envelopes, or carried in briefcases and suitcases. The anonymity, untraceability, and universal acceptance of cash make it useful for many types of criminal activity, including not only corruption, but also drug trafficking, human trafficking, and terrorism. Cash is also indispensable to money laundering, because it both obscures the source of funds and enables money to flow undetected across borders. (As a Europol report observed, “[a]lthough not all use of cash is criminal, all criminals use cash at some stage in the money-laundering process.”) Indeed, as governments and banks increasingly scrutinize electronic transactions, parts of the illicit economy will embrace cash all the more.

Nobody seriously argues for eliminating cash entirely. But there is a simple step that monetary authorities can and should take to make cash-based criminal transactions substantially harder, without substantially impinging on the legitimate cash-based economy: eliminate high-denomination notes.