I respectfully dissent.
It is apparent from everything in the record before us that none of the parties to this suit anticipated the ruling in the Coleman case, supra. Appellants did not plead in the trial court, either directly or indirectly, that the Stephensons had not invoked the jurisdiction of the trial court by alleging and proving they had drilled or proposed to drill a well. A reading of the statement of facts indicates none of the parties were attempting to disprove or prove facts relating to that question.
Under the substantial evidence rule, it is clear that the burden of proof was upon appellant in attempting to set aside the order of the Railroad Commission, to prove the absence of substantial evidence to support such order. Board of Firemen’s Relief & Retirement F. Tr. of Houston v. Marks, 150 Tex. 433, 242 S.W.2d 181 (1951) ; Railroad Commission v. Shell Oil Co., 139 Tex. 66, 161 S.W.2d 1022 (1942).
The statement is made in the majority opinion that the testimony shows the drilling of a well upon the Stephensons’ acreage would have been foolhardy and that the production therefrom would not even pay the operating cost, much less return the investment. That testimony is characterized as “positive”, and the majority concludes the appellants have discharged their burden of showing the Stephensons did not invoke the jurisdiction of the Commission. Such evidence is nothing more than opinion testimony, which does not establish any material fact as a matter of law. Hood v. Texas Indemnity Ins. Co., 146 Tex. 522, 209 S.W.2d 345 (1948).
*380Appellants not only did not mention this matter in the trial court, in its initial brief admitted the Mineral Interest Pooling Act was applicable to the situation before the court and all of the points of error so reflect. It has long been the law in this State that parties are restricted in the appellate court to the theory on which the case was tried in the lower court. Safety Casualty Co. v. Wright, 138 Tex. 492, 160 S.W.2d 238 (1942); State v. J. M. Huber Corp., 145 Tex. 517, 199 S.W.2d 501 (1947).
For these reasons, I would affirm the judgment of the trial court. In any event, I would not render the case, but in the interest of justice, if there was reversible error in the trial court, I would remand the case, so the parties could plead and prove their case under the Coleman case, supra. Scott v. Liebman, 404 S.W.2d 288 (Tex.Sup., 1966).