On April 23, acting U.S. attorney general Todd Blanche signed an order changing the federal classification of medical marijuana . The move, which came at the behest of President Donald Trump and will make the substance a Schedule 3 drug, will bring enormous tax benefits to medical marijuana producers in the 40 states where medical use is legal and may speed research into its effects, experts say.  But it does not legalize marijuana at the federal level, nor does it change the status of marijuana grown for recreational use. Here’s what you need to know. What is a Schedule 3 drug? In the Drug Enforcement Administration (DEA)’s classification system , drugs are assigned a category according to whether they have an accepted medical use and whether they’re likely to cause addiction.…