Sen. Rand Paul (R-KY) is blocking three Senate bills that seek to prohibit new synthetic drugs. Rand spokesperson Moira Bagley confirmed to the Lexington Herald-Leader that he has had a "hold" on the bills for the last three months and that he has no intention of lifting it.
Under Senate "unanimous consent" rules, any senator can place a hold on any bill. A hold doesn't kill a bill, but makes it more difficult for it to pass. A bill with a senatorial hold would require 60 votes to bring it up for consideration over the holding senator's objection.