April 20, 2018— For the second time in as many months, Iran’s “dollar patrol” is on the streets. The country’s currency, the rial, has lost a third of its value on the black market since September. On April 9th it sank to a record low of 61,000 to the dollar (when the official rate was 37,850). The next day the government imposed a rate of 42,000 and vowed to arrest anyone who bought or sold rials for what they are actually worth—as it did during the previous currency crisis, which was only in February.