The Supreme Court (SC) setting aside an order of the National Green Tribunal (NGT), passed based on reports submitted by an Expert Committee and without giving opportunity of being heard to the parties, noted that ‘official notice’ doctrine, according to which “although an authority can rely upon materials familiar to it in its expert capacity without the need formally to introduce them in evidence, nevertheless, the parties ought to be informed of materials so noticed and be given an opportunity to explain or rebut them,” applies to proceedings before NGT.