Voters in four states and Washington, DC, have approved marijuana legalization. But the drug remains illegal under federal law, creating all sorts of legal hurdles that state-legal marijuana businesses have to overcome.

One of those hurdles is federal taxes. Due to a section of the tax code known as 280E, many state-legal marijuana businesses have to pay taxes on their expenses — unlike other legal businesses, which are allowed to deduct them. For some businesses, this can drive their effective tax rates to 70 to 85 percent of their profits, which is enough to force many shops and growers out of business.

“It’s basically a dagger at the throat of the entire legal cannabis industry,” said Steve DeAngelo, co-founder of California-based medical marijuana dispensary Harborside Health Center.

Read more: The federal government is taxing marijuana businesses to death | Vox.