Some manufacturers are marketing supplements that have substances and effects similar to drugs. The FDA is attempting to impose drug status on these supplements and is being challenged in the courts by supplement manufacturers. In this article, I examine the legal debate surrounding the definition and regulation of substances - whether as a drug or a dietary supplement. First, I outline some key differences in the regulation of drugs and supplements and examine the two provisions of DSHEA that blur the distinction. Second, I describe recent at ....