Representative-Taxpayer Doctrine and the Tax Injunction Act:
CO₂ Committee v. Montezuma County (10th Cir. 2025)

1. Introduction

In CO₂ Committee, Inc. v. Montezuma County, the United States Court of Appeals for the Tenth Circuit confronted an increasingly common post-shale-boom dispute: can minority, non-operating owners of an oil-and-gas “unit” bypass the unit operator and bring a federal civil-rights challenge to a state property-tax assessment that was levied on the operator? The panel—Judges Bacharach, Phillips and Federico—answered no, holding that the Tax Injunction Act of 1937 (TIA), 28 U.S.C. § 1341, strips federal courts of jurisdiction whenever state law provides a “plain, speedy, and efficient” remedy through the representative taxpayer (the unit operator).

The decision harmonises federal-jurisdiction doctrine with Colorado’s statutory “representative tax-payer” scheme for oil-and-gas units and cements a new precedent: standing roadblocks faced by non-taxpayers in state court do not, by themselves, unlock the doors of the federal courthouse. The case thus strengthens the jurisdiction-limiting force of the TIA and signals to fractional interest owners that their proper forum is the state system—usually by working through the operator or by suing the operator directly—not the federal courts.

2. Summary of the Judgment

The district court dismissed the CO₂ Committee’s § 1983 suit for lack of subject-matter jurisdiction under the TIA.
On appeal, the Committee argued that (i) Colorado failed to supply a “plain, speedy, and efficient” remedy because the state supreme court had denied the Committee standing, and (ii) the district court failed to accept all complaint allegations as true.
The Tenth Circuit affirmed, holding:
- The challenged levy is indisputably a “tax” within the TIA.
- Colorado’s statutory regime, which makes the unit operator the sole taxpayer and litigation representative, affords a procedurally adequate remedy—even if the Committee itself lacked standing.
- Dismissal of the state case on standing grounds does not convert an adequate procedure into an inadequate one.
- The district court correctly treated the Committee’s assertions about the inadequacy of state remedies as legal conclusions, not facts.

3. Analysis

3.1 Precedents Cited

The panel weaved together federal and Colorado authorities:

Rosewell v. LaSalle National Bank, 450 U.S. 503 (1981) – cornerstone TIA case; confirms that as long as a taxpayer could obtain a full judicial hearing in state court, federal jurisdiction must yield.
Arkansas v. Farm Credit Services, 520 U.S. 821 (1997) and Marcus v. Kansas Dep’t of Revenue, 170 F.3d 1305 (10th Cir. 1999) – emphasise the TIA as a “broad jurisdictional barrier.”
Brooks v. Nance, 801 F.2d 1237 (10th Cir. 1986) – extends the TIA to damages and declaratory relief.
Cities Service Gas Co. v. Okla. Tax Comm’n, 656 F.2d 584 (10th Cir. 1981) – holds that the adequacy inquiry is procedural, not substantive; echoed by the present panel.
Colorado precedents:
- Kinder Morgan CO₂ Co. v. Montezuma County, 396 P.3d 657 (Colo. 2017) – upholds the retroactive assessment.
- Colorado Property Tax Administrator v. CO₂ Committee, 527 P.3d 371 (Colo. 2023) – denies standing to non-operating fractional interest owners; establishes operator-only notice and challenge regime.
- Liebhardt v. Dep’t of Revenue, 229 P.2d 655 (Colo. 1951) – cited to show waiver when statutory tax remedies are not pursued.

By invoking Rosewell and Cities Service, the panel underscored that the adequacy of the state remedy is judged procedurally. The Colorado cases, particularly the 2023 CO₂ Committee decision, supplied the critical premise: under state law the unit operator alone is the taxpayer, so the Committee’s quarrel is indirectly with its own operator, not with the county.

3.2 Legal Reasoning

Is the levy a “tax”?
The assessment against Kinder Morgan’s oil-and-gas interests fits squarely within traditional definitions of a tax: it was imposed by a sovereign for revenue, not to regulate behaviour.
Scope of the TIA.
The TIA forbids federal suits that would “enjoin, suspend or restrain” state-tax collection whenever a “plain, speedy, and efficient” state remedy exists. The panel reiterated that the statute also bars damages and declaratory relief (not just injunctions).
Narrow reading of the exception.
Following Supreme Court instructions, the panel construed the exception narrowly. The mere fact that the Committee lost on standing grounds in state court did not render the remedy procedurally inadequate:
- Colorado provided a clear path—through the operator—to contest the assessment.
- The Committee could still sue Kinder Morgan if it believed the operator misallocated taxes.
Policy and federalism.
Allowing every fractional owner to file overlapping federal challenges would “fracture” Colorado’s tax regime, undermine fiscal stability, and contravene the comity purposes of the TIA.
Pleading-standard objection rejected.
The Committee’s allegation that state remedies were not “plain, speedy, and efficient” was a legal conclusion. Under Ashcroft v. Iqbal, courts need not credit such conclusions at the Rule 12 stage.

3.3 Impact of the Decision

This judgment has several forward-looking effects:

Representative-Taxpayer Doctrine solidified. In jurisdictions that use an operator-centric tax model, fractional owners cannot invoke federal jurisdiction simply because they personally lacked state-court standing.
Clarifies “plain, speedy, and efficient.” The adequacy inquiry remains strictly procedural; unsuccessful outcomes in state court, or even standing dismissals, do not open a federal door.
Strategic guidance to industry participants. Minority interest owners must (i) monitor the operator’s filings, (ii) intervene early at the state administrative level, or (iii) pursue contractual or tort remedies against the operator, rather than leap-frogging into federal court.
Bolsters state taxing autonomy. By refusing to dilute the TIA, the Tenth Circuit reaffirms respect for state fiscal processes—an approach likely to influence future challenges in energy-rich states such as Texas, Oklahoma, and New Mexico.

4. Complex Concepts Simplified

Unit / Unitisation. A legal mechanism that combines multiple working and royalty interests over a common reservoir to maximise production efficiency. One unit operator manages operations and interfaces with regulators.
Non-Operating Fractional Interest Owner. A party that owns a slice of the unit’s output or profits but has no managerial role.
Related-Party Transaction. A deal between entities under common control (e.g., Kinder Morgan and its 50 %-owned pipeline partnership), often subjected to heightened tax scrutiny.
Tax Injunction Act (TIA). Federal statute barring federal courts from interfering with state tax collection when state courts provide an adequate procedural remedy.
“Plain, Speedy, and Efficient Remedy.” A remedy is “plain” if it is certain, “speedy” if timelines are not unreasonably long, and “efficient” if it is structured enough to allow a full hearing and judicial review. It does not guarantee a taxpayer’s success on the merits.
Standing. The legal capacity to bring a lawsuit; under Colorado’s oil-and-gas tax statutes, only the operator has standing to contest an assessment on the unit.

5. Conclusion

CO₂ Committee v. Montezuma County fortifies the Tax Injunction Act’s jurisdictional wall and introduces a clear rule for the oil-and-gas context: where state law designates a representative taxpayer, non-representative interest owners cannot circumvent that scheme by resorting to federal court, even if state standing doctrine keeps them out. The decision promotes comity, protects state revenue streams, and signals to practitioners that future attacks on state tax assessments must respect statutory representative structures or find alternative, state-based avenues for relief. In the broader landscape of federal-state relations, the case exemplifies how federal courts continue to guard state taxing autonomy against expansive § 1983 litigation strategies.

Representative-Taxpayer Doctrine and the Tax Injunction Act: CO2 Committee v. Montezuma County (10th Cir. 2025)