IT IS often said that markets hate uncertainty. America’s marijuana industry is no exception. Earlier this year Jeff Sessions, the country’s attorney-general, rescinded a set of federal guidelines for marijuana-related businesses operating in states where the drug is legal. Now lawmakers and businesses in these states are demanding clarity for an industry that could generate as much as $11bn in revenue in 2018. The financial-services industry may be one of the largest beneficiaries of greater certainty.

Providing banking services to pot-sellers is a risky endeavour. Despite being legal in one form or another in 29 states, marijuana is banned under the federal Controlled Substances Act, and classified as a so-called Schedule 1 drug alongside cocaine and heroin. This is why the vast majority of American banks refuse to do business with the industry, lest they run foul of federal statutes on money-laundering, drug-trafficking and racketeering. As of September 2017, just 400 of America’s 5,700 banks catered to the sector (see chart). Without access to financial services, most marijuana-related businesses operate on a cash-only basis, stashing piles of money in duffel bags and hiring armed guards to protect employees from robberies.

The Obama administration tried to address the issue in 2013 when the Department of Justice

laid out

its priorities for prosecuting marijuana-related crimes, which included preventing marijuana sales to minors and the trafficking of the drug across state lines. The following year, the Treasury

hinted

to banks serving the cannabis industry that they would not be charged if they closely monitored their clients and filed “suspicious-activity reports” documenting relevant transactions. But in January Mr Sessions

rescinded

his predecessor’s pot-friendly policies. The move was not a surprise. In a Senate hearing in 2016, Sessions famously said that “good people don’t smoke marijuana”.

States eager to stimulate their marijuana markets–and the tax revenues that they generate–may take matters into their own hands. California and Massachusetts are considering creating public banks for pot-sellers. And on Capitol Hill, Senator Cory Gardner of Colorado, a Republican, recently announced that the White House has expressed support for legislation allowing states to regulate marijuana. On April 20th Charles Schumer, the Democratic leader in the Senate, is expected to unveil just such a bill.