RIL counsel Harish Salve questioned the legality of a part of an earlier ruling of the Bombay High Court.
He said private pacts between two people cannot bind a corporate entity and its shareholders.
"Admittedly, this document was not placed before the RIL board. Admittedly, it was not mentioned before the court. It was not shown to the RIL shareholders," argued Salve.
He was placing his arguments before a three-judge bench comprising Chief Justice KG Balakrishnan, Justice B Sudershan Reddy and Justice P Sathasivam, which has been hearing the matter.
Salve also said the family pact had envisaged it would only serve as a guiding document to arrive at the suitable arrangement for gas supply and that the two brothers would arrive at a suitable agreement.
The dispute is over the supply of 28 million units of natural gas for 17 years at $2.34 per unit to Anil Ambani-led Reliance Natural Resources (RNRL) from the gas fields off the Andhra Pradesh coast, awarded to Mukesh Ambani-led RIL.