Restrictions as to imposition of tax on the sale or purchase of goods

(1) No law of a State shall impose, or authorise the imposition of, a tax on 1[the supply of goods or of services or both, where such supply takes place]—

(a) outside the State; or

(b) in the course of the import of the 2[goods or services or both] into, or export of the 2[goods or services or both] out of, the territory of India. [* * * *]

[(2) Parliament may by law formulate principles for determining when a [supply of goods or of services or both] in any of the ways mentioned in clause (1).

[(3) * * * *]