Patents Act, 1970
68. Assignments, etc. not to be valid unless in writing and registered
An assignment of a patent or of a share in a patent, a mortgage, license or the creation of any other interest or of a share in a patent, a mortgage, license or the creation of any other interest in a patent shall not be valid unless the same were in writing and the agreement between the parties concerned is reduced to the form of a document embodying all the terms and conditions governing their rights and obligations and the application for registration of such document is filed in the prescribed manner with the Controller within six months from the commencement of this Act or the execution of the document, whichever is later or within such further period not exceeding six months in the aggregate as the Controller on application made in the prescribed manner allows:
PROVIDED that the document shall, when registered, have effect from the date of its execution.