Section 297(3) in The Mumbai Municipal Corporation Act, 1888
(3)No person shall construct any portion of any building within the regular line of the street except with the written permission of the Commissioner, who shall, in every case in which he gives such permission, at the same time report his reasons in writing to the [Standing Committee] [These words were substituted for the words 'Mayor-in-council' by Maharashtra 27 of 1999, Section 109, (w.e.f. 23-4-1999)].]