131. Original jurisdiction of the Supreme Court .—Subject to the provisions of this Constitution, the Supreme Court shall, to the exclusion of any other court, have original jurisdiction in any dispute—
(a) between the Government of India and one or more States; or
(b) between the Government of India and any State or States on one side and one or more other States on the other; or
(c) between two or more States, if and in so far as the dispute involves any question (whether of law or fact) on which the existence or extent of a legal right depends: 1[Provided that the said jurisdiction shall not extend to a dispute arising out of any treaty, agreement, covenant, engagement, sanad or other similar instrument which, having been entered into or executed before the commencement of this Constitution, continues in operation after such commencement, or which provides that the said jurisdiction shall not extend to such a dispute.]