In Guran Ditta v. Ram Ditta the phrase "substantial question of law' as it was employed in the last clause of the then existing Section 100 CPC (since omitted by the Amendment Act, 1973) came up for consideration and their Lordships held that it did not mean a substantial question of general importance but a substantial question of law which was involved in the case.
In Sir Chunilal case the Constitution Bench expressed agreement with the following view taken by a Full Bench of the Madras High Court in Rimmalapudi Subba Rao v. Noony Veeraju(Sir Chunilal case, SCR p.557)
"When a question of law is fairly arguable, where there is room for difference of opinion on it or where the Court thought it necessary to deal with that question at some length and discuss alternative views, then the question would be a substantial question of law. On the other hand if the question was practically covered by the decision of the highest court or if the general principles to be applied in determining the question are well settled and the only question was of applying those principles to the particular fact of the case it would not be a substantial question of law."
23. To be "substantial" a question of law must be debatable, not previously settled by law of the land or a binding precedent, and must have a material bearing on the decision of the case, if answered either way, insofar as the rights of the parties before it are concerned. To be a question of law "involving in the case" there must be first a foundation for it laid in the pleadings and the question should emerge from the sustainable findings of fact arrived at by court of facts and it must be necessary to decide that question of law for a just and proper decision of the case. An entirely new point raised for the first time before the High Court is not a question involved in the case unless it goes to the root of the matter. It will, therefore, depend on the facts and circumstance of each case whether a question of law his a substantial one and involved in the case or not, the paramount overall consideration being the need for striking a judicious balance between the indispensable obligation to do justice at all stages and impelling necessity of avoiding prolongation in the life of any lis.(See Santosh Hazari v. Purushottam Tiwari).