Phillips Petroleum Company, Gpm Gas Corporation, Phillips Gas Marketing Company, Phillips Gas Company, and Gpm Gas Trading Company v. Royce Yarbrough, 405 S.W.3d 70

Royalty owners sue Phillips for underpaid oil and gas royalties; three prior subclasses certified, later decertified, Bowden remanded with res judicata directive; on remand Yarbrough as GRA class representative alleged implied covenant to market breached by Phillips; trial court allowed new implied-covenant claim without amended certification or hearing; Phillips challenged via interlocutory appeal and mandamus; Texas Supreme Court granted review and reversed the appellate dismissal, remanding for rigorous Rule 42 analysis and res judicata evaluation.
Bowden held GRAs unambiguous and certifiable as a class; subsumed disputes over the implied covenant in Bowden were distinct from the GRA class claim; remand required a res judicata analysis for abandoned claims.
GRAs define a weighted-average-price calculation; Bowden approved GRA class predominance, rejecting decertification; remand instructed consideration of res judicata effects on certification.
The trial court approved a plan allowing the implied-covenant claim to proceed for the GRA class without a separate certification motion; the appellate court dismissed Phillips’s mandamus and interlocutory appeal for lack of jurisdiction, which this Court reversed.
This Court concludes certification requires a rigorous Rule 42 analysis including res judicata effects; the GRA class may proceed on an implied-covenant theory only if properly certified under Rule 42.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether adding an implied covenant claim changes the class’s fundamental nature	Yarbrough argues new claim expands class scope	Phillips argues fundamental change requires new certification	Abuse: trial court must conduct rigorous analysis before certification
Whether the order allowing the implied covenants claim is subject to interlocutory appeal	Jurisdiction exists under 51.014(a)(3) as it alters class scope	No fundamental alteration; appeal improper	Interlocutory appeal jurisdiction exists; appellate review proper
Whether the trial court failed to address res judicata effects in certification analysis	Res judicata must preclude abandoned claims and affect certification	Res judicata adequately addressed by class definition	Trial court abused by not conducting rigorous res judicata analysis and remand required

Bowden v. Phillips Petrol. Co., 247 S.W.3d 690 (Tex. 2008) (reversed in part; analyzed res judicata and class certification standards under Rule 42; GRA class predominance)
Citizens Ins. Co. v. Daccach, 217 S.W.3d 430 (Tex. 2007) (class actions follow preclusion rules; abandoned claims affect certification considerations)
De Los Santos v. Occidental Chem. Corp., 933 S.W.2d 493 (Tex. 1996) (interlocutory appeal when order alters fundamental class nature)
Bally Total Fitness Corp. v. Jackson, 53 S.W.3d 352 (Tex. 2001) (narrow exception to appealability for class-certification-related orders)
Henry Schein, Inc. v. Stromboe, 102 S.W.3d 675 (Tex. 2002) (rigorous Rule 42 analysis required for class certification)
Sw. Ref. Co. v. Bernal, 22 S.W.3d 425 (Tex. 2000) (affirming need for rigorous analysis in certification)