There are growing signs that the government wants to ban cash, or strictly cut back on its use — another “conspiracy theory” about to become conspiracy fact. Our subject today is the single legal industry that might be most affected.

California has a provision for medical marijuana use. The state taxes the product, and dispensaries have expenses to pay. But all the transactions must be done in cash.

Why? Because Uncle Sam, who is starting to look way less friendly than he did on military recruiting posters 60 years ago, says so. Even in states that have legalized it, the feds consider marijuana a Schedule 1 drug like meth and cocaine. Thus, dispensaries have no access to the banking system. No deposits, no checks, no credit cards.

The Guardian of London quoted the director of a nonprofit dispensary: “We’ve been a cash industry forever and it has been quite a problem. We don’t want to drive around town paying our bills in cash. We want to be able to just go to the bank.”

Things get strangest in the tax collection area, where businesses can bring in bags of currency on “cash day.” That makes the tax offices reek of pot, or perhaps of dryer sheets as dispensaries try to remove the odor. (Presumably the laws on money laundering, while overly broad, don’t extend that far.)

Meanwhile, former Treasury secretary and generally worthless academic Larry Summers wrote an op-ed in The Washington Post suggesting that high-denomination cashs (500-euro note and $100 bill) be banned. The laughable reasoning is that only criminals use such bills.

Make no mistake: Proposals like this are not about crime. They are about imposing currency controls and creating an electronic trail of every transaction. They are about robbing you of freedom.