Fortune: “Legalized marijuana sales are spreading across the U.S., but the industry’s businesses are facing steep federal tax bills thanks to a wrinkle in the tax code dating back to the 1980’s. . . . In 1982, Congress enacted Section 280E of the federal Tax Code to prevent drug traffickers from being able to claim business expenses related to illicit dealings on their federal tax returns. . . . many marijuana business owners end up paying effective tax rates of anywhere from 40% to 70%