Section 51 of the Principal Act is amended by omitting subsection (3) and substituting the following subsection:

(3)  The decision of a planning authority on an application referred to in subsection (1A) or (1B) is to be made by reference –

(a) to the provisions of the planning scheme or special planning order as in force at the date of that decision; or

(b) if the planning authority has been required under section 28(1)(a) to modify a draft planning scheme and that draft planning scheme has not been approved by the Commission at the date of that decision, to the provisions of the draft planning scheme modified as required; or

(c) if the planning authority has been required under section 41(a) to modify, or alter to a substantial degree, a draft amendment to a planning scheme and that draft amendment has not become operative at the date of that decision, to the provisions of the planning scheme as they would be if the draft amendment modified, or altered to a substantial degree, as required had become operative.