In Railroad Commission of Texas v. Lone Star Gas Co., 844 S.W.2d 679, 690, 36 Tex. Sup. Ct. J. 436 (Tex. 1992) the Court held that the separate existence of corporations was not disregarded "when affiliated purchasers use the same pipeline to transport gas." In that case, the Railroad Commission had promulgated rules governing pipeline companies such as RGVG and Southern Union and their affiliated special marketing programs (SMPs) such as Reata, L.P. and Mercado. Under the Commission's rules and regulations, separate corporate entities were created as SMPs to buy cheaper spot-market gas and sell it to the affiliated pipelines' customers. Id. at 684. The rules that were challenged in Lone Star treated pipeline companies and their affiliated SMPs as one entity for purposes of preventing discriminatory production and taking of natural gas when the pipeline and the SMP used the same pipeline system, unless the SMP qualified as a first purchaser or applied for a hardship exception. The Court held that operating in this manner, as required by the Commission's rules, did not disregard the separate corporate structures of the pipeline company and its SMP. Id. at 690