Neither the United States Department of Justice nor the United States health department have labeled Mephedrone as a Club Drug.
At the turn of the century MDMA was what the club kids called E, X or ecstasy(PDF; however, analogs such as MDA (Love Drug) were outlawed. The technical variances make it legal to enforce a classification of drugs already outlawed by the Federal Government.
Over the last few years compounds have surfaced on the market too distant chemically to be labeled a a Substance I Scheduled Hallucinogen according to the enforcement capacity of the U.S. Controlled Substances Act.
A new category of drugs often marketed as bath salts to avoid Food and Drug Administration are being resold as meow, plant food ,molly (a powder form of Extasy)and a cocaine alternative.
February of this year the United States Department of Health issued the following warning proceeding numerous hospitalization from the new category of drug.
On August 29th, the state of Missouri became the 32 state to outlaw the new class of synthetic drug. Other Foreign governments including the Europeon Union are enforcing a ban on mephedrone and similar analogs.
Presidential Politics: Bath Salts Emerging and Dangerous says U.S. Department of Health and Human Services - National Institute on Drug Abuse