The Texas Supreme Court on Friday said that a group of bipartisan Lone Star State legislators can't use its committee's subpoena power to pause the execution of a man convicted based on a "shaken baby syndrome" diagnosis.

The Texas justices didn't weigh in on the guilt or innocence of Robert Leslie Roberson III in its 31-page opinion, only whether Texas Legislatures had the ability to "override" other branches of government in attempting to pause Roberson's execution.

"This is not an instance of 'two ships passing in the night,'" Justice Evan A. Young wrote for the court, referring to Texas lawmakers' subpoena "overlapping" with Roberson's execution date. "It involves multiple ships demanding the same moorings at the same dock — a circumstance that if unchanged promises a head-on collision."

"The committee knew that Roberson was scheduled for that execution and could have availed itself of any number of past opportunities to obtain his testimony," Justice Young wrote, noting that the execution was initially scheduled for July and that the work leading up to an execution is often decades in the making.

"The facts allegedly giving rise to a need for Roberson's testimony have been public knowledge for years," the opinion continues. "The last-minute subpoena intruded on the duties of the judicial branch to adjudicate and impose penalties for offenses, as well as the duties of the executive branch to execute judicial sentences and determine the propriety of clemency."

Roberson, 57, was convicted of killing his 2-year-old daughter in 2002. Doctors and a medical examiner had found that she had internal bleeding and brain swelling that were signs of what is known as shaken baby syndrome, which is caused by violently shaking a child.

Roberson was sentenced to death in 2003 and was unsuccessful in overturning his conviction after several appellate proceedings in the years following.

His case has garnered national attention in recent weeks as Roberson has pushed for a stay of his execution based on Texas' "junk science law," which gives defendants a path to overturn their convictions based on debunked scientific research. Roberson alleged that the expert testimony prosecutors relied on for his conviction has since been discredited, pointing to new science surrounding abusive head trauma and new evidence from his daughter's autopsy report.

As the Texas Court of Criminal Appeals ruled on Oct. 17 — the scheduled date of Roberson's execution — that Roberson's execution could proceed, a group of Texas lawmakers issued a subpoena to Roberson requiring him to appear at the Texas Capitol and testify before the Texas House of Representatives Criminal Jurisprudence Committee.

Rep. Joe Moody, D-El Paso and chair of the Texas House Committee on Criminal Jurisprudence, told Law360 that Texas House rules require a five-day notice for all hearings, meaning Roberson could not have been called to testify until after his execution date. Lawmakers turned to a district court in Travis County to allow Roberson to comply with the subpoena, which initially granted a temporary restraining order.

Texas lawmakers ultimately took their case over the subpoena to the high court, which issued a stay order that "temporarily enjoined impairment of Roberson's ability to comply with the subpoena," effectively halting his execution.

The high court stressed Friday that its involvement in the case is not an improper exercise of power over criminal habeas corpus proceedings.

"Despite its high-profile and emotion-laden subject matter, this case is not analytically different for jurisdictional purposes," the court wrote. "With competing claims from (and in some instances within) the three branches of government, it falls to this court to resolve as a matter of law which branch's authority must prevail in this situation."

An order from the Texas Supreme Court, Justice Young noted, would not require the Texas Department of Criminal Justice to present Roberson in court nor to "question the lawfulness of Roberson's restraint or sentence of death any more than if Roberson (or any other inmate) were brought into a court to testify as a witness in another defendant's trial, as is authorized by law."

The high court spent the majority of its opinion weighing the interests of the three branches of government, which "converge" in the death penalty context, noting that the Texas Legislature's subpoena power "is purposefully and necessarily broad" but "not absolute."

"No matter the legislators' motivations, a last-minute subpoena in this specific context threatens to intrude on the executive prerogative" of complying with the judicial branch's "death warrant," which authorizes a person's execution. "Even when other governmental actions are valid in and of themselves, they can impinge on the executive power, thus increasing the burden to establish why the executive branch should yield rather than the other way around."

The Supreme Court emphasized that it does not "repudiate legislative investigatory power," leaving legislators the possibility of seeking Roberson's testimony at a future date.

"If the committee still wishes to obtain his testimony, we assume that the department can reasonably accommodate a new subpoena," Justice Evan A. Young wrote for the court. "To the extent that an accommodation is not forthcoming, so long as a subpoena issues in a way that does not inevitably block a scheduled execution, nothing in our holding prevents the committee from pursuing judicial relief in the ordinary way to compel a witness's testimony."

In a statement posted to X, Reps. Jeff Leach, R-Plano, and Moody said they were "grateful" for the court's consideration of their case.

"In holding that a legislative subpoena cannot delay an execution — never our specific intention — the Supreme Court also rightfully agreed that our legislative subpoena and this suit were valid," the statement reads. "Further, the Supreme Court strongly reinforced our belief that our committee can indeed obtain Mr. Roberson's testimony and made clear that it expects the executive branch of government to accommodate us in doing so. That has been our position all along, and we look forward to working with the executive branch to do just that."

The case is In Re Texas House of Representatives, case number 24-0884, in the Texas Supreme Court. 

--Editing by Alyssa Miller and Amy French.

Update: This story has been updated with additional information from the court's opinion.