Exemption from taxes on electricity protects central government and specified railway consumption from state-imposed consumption or sale taxes. No State law may impose or authorise a tax on the consumption or sale of electricity consumed by the Government of India or sold to it, except as Parliament may provide; the same protection applies to electricity consumed in the construction, maintenance or operation of railways by the Government of India or railway companies, and any State law taxing the sale of electricity must ensure the price to the Government or such railway companies is reduced by the amount of the tax compared with prices to other substantial consumers.