Xcel Energy cannot rely upon a rate-setting document to broadly immunize itself from liability against electrocutions, the Colorado Supreme Court ruled on Monday.

The justices originally heard the electrocution-related lawsuit from Francisco Cuevas to decide whether Xcel’s tariff, which sets the rates and terms of service for its customers, shielded the utility from liability when its power lines injure someone who is not a customer.

But by 5-1, the Supreme Court did not decide whether the tariff actually went that far, instead concluding that the Colorado Public Utilities Commission had no authority, to begin with, to approve a tariff that immunizes Xcel under those circumstances.

While the state constitution and law “grant broad authority to the PUC to regulate utilities’ facilities, services, rates, and charges, nothing in those provisions either expressly or by necessary implication grants the PUC the authority to limit a utility’s liability to non-customers,” wrote Justice Richard L. Gabriel in the Jan. 26 opinion.

Chief Justice Monica M. Márquez dissented. She did not believe the Public Utilities Commission needed specific authorization to approve a tariff with immunity because its authority is broad by default.

“As relevant here, although it has the power to do so, the legislature has not restricted the PUC’s authority to approve tariff provisions that limit a utility’s liability to non-customers,” she wrote. “Accordingly, the PUC retains such authority.”

Cuevas, the owner of Outdoor Design Landscaping, was hanging Christmas lights at a Lakewood woman’s home in late 2017 when he received a debilitating shock from nearby power lines. On the theory that the close proximity of the power lines electrified the tree, Cuevas sued the homeowner and Xcel for his injuries.

The Court of Appeals allowed the lawsuit to proceed in part, reasoning that Xcel’s tariff could not, on its own, provide immunity in such scenarios.

Tariffs have “contractual roots and regulate a utility’s provision of services to its customers,” wrote Judge Timothy J. Schutz, adding the legislature had said nothing about the wider immunity Xcel claimed it had.

Xcel appealed, pointing out the Colorado Constitution gives “all power to regulate the facilities, service and rates and charges” of utilities to the Public Utilities Commission — which approved the tariff containing immunity language for Xcel. To the Supreme Court, Xcel argued its tariff immunity for “injury to persons” meant what it said, without any limitation to customers. The company noted that tariffs have the force of law and argued that the Court of Appeals was wrong to view them as merely a contract between the utility and the customer.

But during oral arguments, multiple justices were uncomfortable with the idea that the commission’s constitutional power included granting immunity for electrocutions seemingly without restriction.

“It’s highly troubling to say that a tariff can give a utility the right to limit its own liability to anybody in the world,” said Gabriel.

For its part, Cuevas’ company, Outdoor Design, appealed the Court of Appeals’ determination that it violated the High Voltage Safety Act by engaging in activity that reasonably could have brought employees within 10 feet of the power lines, yet failed to notify Xcel. That meant Outdoor Design would have to reimburse Xcel if a jury found the utility liable for Cuevas’ injuries — an outcome that Cuevas’ attorney acknowledged would end the lawsuit.

The Supreme Court largely upheld the appellate panel’s decision, while going further and concluding the Public Utilities Commission could not approve of a tariff that includes immunity for non-customers’ injuries, notwithstanding the narrow exception for defective power lines.

Upholding the tariff language “would afford the PUC essentially limitless regulatory power, including the power to grant utilities full immunity from liability to any injured persons or entities,” wrote Gabriel.

Márquez believed the immunity in the tariff was constrained to “highly specific (and relatively unlikely) circumstances.” Because lawmakers had not restricted the Public Utilities Commission’s authority to approve such a provision, she concluded the constitution allows for it.

The case is Public Service Company of Colorado v. Outdoor Design Landscaping, LLC et al.