The Assam Reorganisation (Meghalaya) Act, 1969
18. Duration of Legislative Assembly.-
The Legislative Assembly, unless sooner dissolved, shall continue for five years from the date appointed for its first meeting and no longer, and the expiration of the said period of five years shall operate as a dissolution of the Legislative Assembly:
Provided that the said period may, while a Proclamation of Emergency issued under clause (1) of article 352 is in operation, be extended by Parliament by law for a period not exceeding one year at a time and not extending in any case beyond a period of six months after the Proclamation has ceased to operate.