Justice Susan Blanco’s first solo opinion as a new member of the Colorado Supreme Court made clear her view of the guardrails that keep the state’s highest court tethered to the issues it is asked to decide.

On Monday, the court issued a 4-3 decision in a criminal appeal. Blanco, while part of the majority, authored her own opinion, describing where she stands on a key principle guiding appellate courts. The “party presentation principle,” as it is known, establishes that the parties to a case are the ones who frame the issues for the courts to adjudicate.

Blanco offered an enthusiastic defense of the principle, prioritizing it over other obligations an appellate judge may have.

“We rely on these procedures to provide a fair opportunity for preparation and to keep the judiciary in its adjudicatory lane,” she wrote. “There is a dire cost to everyone when courts deviate from these principles, which are only worthwhile if they are actively maintained.”

The underlying case, People v. Lulei, questioned whether a detective improperly re-initiated an interrogation of a suspect who previously invoked his constitutional right to counsel. Although the Denver District Attorney’s Office did not initially argue that the suspect had not validly invoked his rights because he was not in custody, the Supreme Court’s majority ultimately concluded that the lack of custody was the deciding factor.

The three dissenting justices would have refused to address the issue because the prosecution neglected to raise it. The lineup — consisting of Justices Richard L. Gabriel, William W. Hood III, and Maria E. Berkenkotter — was the same as a 2024 decision in which the three similarly accused the majority of violating the party presentation principle to resolve an appeal.

“If the parties raise these issues and the court goes off on its own and addresses something, there’s a question of whether the parties got a full and fair opportunity to address the issue,” said Gabriel, the most vocal proponent of the principle, at a legal event last year. “I tend to think it reflects judicial restraint, judicial humility, and the proper role of the court.”

Blanco, in her concurrence in the Lulei case, described the unique circumstances that, in her view, resulted in the custody issue being placed “barely” in front of the court for review. Those included the defense’s request to address the topic in writing after oral arguments.

However, she declined to endorse the majority’s view that courts can deviate from the issues presented by the parties whenever they have a “fundamental obligation to ascertain controlling law.” In doing so, she appeared to cast doubt on that assumption.

“I cannot square this proposed obligation with parties’ responsibility to advance ‘the facts and argument entitling them to relief,'” wrote Blanco. Courts “should not place the cart (deciding legal questions) before the horse (confining decisions to contested issues).”

She added that a court’s desire to ascertain the correct law “runs the risk” of deciding the merits of an issue not before it.

Attorney Geoffrey Klingsporn said it is uncommon for the two principles to conflict, but that there must be flexibility when they do.

“Let’s take an extreme case — if both sides are arguing based on the wrong legal standard because they both missed the implications of an intervening Supreme Court case that changed the standard,” he said. “So, all the way through the district court and the appellate briefing, they were arguing facts under the wrong legal standard. And then it got up to the Supreme Court, and one of the justices and their clerks noticed, ‘Hey, they’re applying the wrong three-factor test. It’s actually a five-factor test now.’ I think it would not be the correct way for the Supreme Court to just say, ‘Well, we know the real test is a five-factor test, so we’re going to use the three-factor test even though we know that it’s wrong.'”

On the other hand, he continued, “there’s also the longstanding principle that the court’s not going to tell the lawyers how to try their case or argue their case.”

Klingsporn, who has also compiled statistics about the Colorado Supreme Court since 2013, said Blanco’s authorship of a concurring opinion less than a month after joining the court was the earliest a new member had published a solo opinion since Hood joined in 2014.

Blanco spoke to Colorado Politics before the governor selected her in February, and she said the citizen-led nominating commission asked her how she felt about being the lone person to write separately.

“I anticipate there are gonna be times I may see things differently, and I think it’s just part of the responsibility to speak up and write, even if you’re the dissenting, lone person who has to do that,” said Blanco. “I don’t know how it will be when I am there. But I imagine there are circumstances where I might be the only person who sees things a certain way. And I’d really want to be thoughtful about listening to the others, but I am prepared to be the only one in those circumstances if need be.”