The Maritime Labor Convention of 2006 became effective on 20 August 2013: Are the authorities ready? Consider that MLC 2006 Regulation 1.2-Medical certificate. Standard A1.2 states that “a competent authority shall require prior to beginning work on a ship, seafarer’s hold a valid medical certificate.” Under paragraph 7a of that same regulation it further states that “a medical certificate shall be valid for a maximum period of TWO YEARS.” That requirement also became official for U.S.