Perhaps people recall from high school history class that Mr. Roosevelt attempted to "stack" the SCOTUS with liberal Justices. You might also recall hearing that his attempt failed.I don't know why people make that claim. Wickard v Filburn 317 U.S. 111 (1942) is the controlling legal authority which gives the Federal government their power to enact and enforce the laws of drugs prohibition. 8 of 9 Justices that voted in favor of that decision were appointed by Mr. Roosevelt. Oh my no, he didn't succeed in "stacking" the SCOTUS.
BTW the Marihuana Tax Act was struck down buy the SCOTUS in Leary V United States of America, 395 U.S. 6 (1969).