Hydel power generating industries in India cannot be asked to pay pollution tax without the Parliament including them within the purview of Water (Prevention and Control of Pollution) Cess Act of 1977, the Supreme Court has ruled. The act, promulgated with a view to tax polluting units, had excluded the hydel power generating industries. However, the Union government decided to amend the law and tax these industries. This decision was challenged by the National Hydro Electric Power Corporation, which took the matter to the courts. The apex court ruled that as the Parliament has not yet approved the amendment, the tax could not be imposed.