Existing law definition under GST clarifies that pre GST statutes and instruments imposing duties or taxes on goods or services remain relevant. Existing law for GST purposes encompasses any pre GST statute, notification, order, rule or regulation that provided for levy and collection of duty or tax on goods or services, including instruments made by Parliament or any authority or person empowered to make such instruments prior to the commencement of the GST regime; the definition operates as a transitional and interpretive device.