Md. Const. art. XVI, § 3
(b) If more than one-third, but less than the full number of signatures required to complete any referendum petition against any law passed by the General Assembly, be filed with the Secretary of State before the first day of June, the time for the law to take effect and for filing the remainder of signatures to complete the petition shall be extended to the thirtieth day of the same month, with like effect.
If an Act is passed less than 45 days prior to June 1, it may not become effective sooner than 31 days after its passage. To bring this Act to referendum, the first one-third of the required number of signatures to a petition shall be submitted within 30 days after its passage. If the first one-third of the required number of signatures is submitted to the Secretary of State within 30 days after its passage, the time for the Act to take effect and for filing the remainder of the signatures to complete the petition shall be extended for an additional 30 days.
Acts 1914, c. 673, ratified Nov. 2, 1915; Acts 1962, c. 6, ratified Nov. 6, 1962; Acts 1976, c. 548, ratified Nov. 2, 1976.