In Questar Gas Co. v. Utah Pub. Serv. Comm'n, 2001 UT 93, 34 P.3d 218, the Court set aside the Commission's report and order, holding that Questar Gas's use of account 191 to recover costs was not limited to requests under the pass-through statute. In that case, Questar had argued that the use of account 191 "is . . . a separate mechanism--with its own procedures--used to facilitate the transfer of certain unexpected costs on a dollar-for-dollar basis from the utility to its customer." Id. The Court based the decision on the Commission's own prior practices, noting that the Commission, when reviewing Questar Gas's use of account 191, determined in an informal proceeding whether the resulting rates were "just, reasonable and cost justified" and whether their approval was "in the public interest." Id. The Court held, further, that the 191 account mechanism should yield a just and reasonable rate because Questar Gas's tariff, previously approved by the Commission, already set out the formula by which rates would be determined, based on the costs and revenues assigned to different accounts. Id. The Court remanded the case to the Commission for further consideration in accord with the 191 account mechanism procedures. Id. at P20.