Section 77 in The North-Eastern Areas (Reorganisation) Act, 1971
77. Territorial extent of laws.
The provisions of Part II shall not be deemed to have effected any change in the territories to which any law in force immediately before the appointed day extends or applies, and the territorial references in any such law to the existing State of Assam or the autonomous State of Meghalaya or the Union territory of Manipur or the Union territory of Tripura or the North-East Frontier Agency shall, until otherwise provided by a competent Legislature or other competent authority, be construed as meaning the territories within that State or autonomous State or Union territory or Agency immediately before the appointed day.
