A bipartisan group of Lone Star State legislators stopped what would have been the nation's first execution for a conviction based on a "shaken baby syndrome" diagnosis by raising a novel separation-of-powers question about whether legislative subpoenas or death warrants carry more authority.

Robert Leslie Roberson III's life was spared for the moment Thursday night when a Texas Supreme Court ruling reinstated a temporary restraining order barring his execution by lethal injection at least until after he testifies Monday before the Texas House of Representatives' Criminal Jurisprudence Committee. Lawmakers issued the subpoena as part of their investigation into the criminal justice system's failure to stop Texas from killing Roberson, who they believe is innocent.

Roberson, 57, was convicted of killing his 2-year-old daughter, Nikki Curtis, in 2002 after emergency room doctors and a medical examiner ruled that her internal bleeding and brain swelling were clear signs of what was then called shaken baby syndrome, a serious and sometimes fatal form of brain injury that was believed at the time to be caused by violently shaking a child. Roberson has challenged his conviction since 2016, alleging it is based on now-debunked science and that he is actually innocent.

"While some courthouses may have failed him, the Texas House has not," lawmakers said in a statement released shortly after the Texas Supreme Court issued its order. "We're deeply grateful to the Texas Supreme Court for respecting the role of the Texas legislature in such consequential matters. We look forward to welcoming Robert to the Texas Capitol, and along with 31 million Texans, finally giving him — and the truth — a chance to be heard."

Thursday's court victory was the product of months of bipartisan collaboration that culminated in a two-week race against the clock, state Rep. Joe Moody, D-El Paso and chair of the Texas House Committee on Criminal Jurisprudence, told Law360 in an interview. After a disappointing ruling from the state's Court of Criminal Appeals, which held in early October that officials could proceed with Roberson's execution, Moody said it became clear a legislative subpoena was the only way forward.

"We didn't know what that would look like, to have a valid legislative subpoena and a valid execution warrant, two things with equal dignity under the law," he said. "The lawyers told us this is unprecedented, that we were in uncharted territory."

The decision to issue a subpoena for Roberson's testimony was unanimous among the five Republican and two Democratic members present at the vote Wednesday. But under the Texas House's procedural rules, which require a five-day notice for all hearings, the committee can't hear testimony from Roberson until Monday despite the fact that he was scheduled to be executed Thursday.

So the lawmakers turned to a district court in Travis County and requested a temporary restraining order that would allow them to enforce their subpoena. They successfully argued that separation-of-powers principles required the order to ensure that the state Legislature's constitutional power to investigate couldn't be undercut by a coequal branch of government.

After a stop at the Texas Court of Criminal Appeals, the state's highest criminal court, which wiped out the temporary restraining order, the lawmakers took their case to the Texas Supreme Court. That court, which usually has no power to review TCCA decisions, found it had jurisdiction because the separation-of-powers question was one of civil law. The Texas justices then unanimously held that the district court acted within its discretion and ruled the restraining order would remain in place.

Moody said the committee is working on the logistics of having Roberson visit the state Capitol on Monday.

Roberson's conviction and the subsequent denials of his post-conviction relief "shined a light" on the misapplication of a Texas law that's supposed to give defendants a pathway to overturn convictions based on discredited scientific research, Moody said at a hearing before the committee's subpoena vote Wednesday. He told Law360 that Roberson will be invited to discuss his experience with that appellate process as well as specifics related to his case.

"The focal point became [Roberson's] case, but the problem extends further," Moody told Law360.

Texas' law, which is referred to as the "junk science law" and was enacted in 2013, is aimed at addressing situations like Roberson's. But so far the TCCA has refused to apply the rule in a death penalty case, according to advocacy group Texas Defender Service.

Republican state Rep. Brian Harrison of Waxahachie — whom Moody described as someone who "couldn't be further away from me on the political spectrum" — expressed "grave concerns" about the TCCA's treatment of the junk science law at Wednesday's hearing.

"It is incumbent on those of us in the Legislature to make sure that the laws that we pass are being faithfully adhered to, implemented and interpreted by all parties who are supposed to be bound by them," Harrison said. "And in this case, that absolutely includes the courts."

Roberson's conviction was almost entirely based on expert testimony that Curtis had the so-called shaken baby syndrome "triad" of symptoms at the time of her death. According to court filings, in 2002, doctors were told that a patient who showed signs of bleeding between their brain and skull, hemorrhaging near their eyes and brain swelling should be presumed to have the condition, now known as abusive head trauma.

But the diagnostic guidelines have changed since then, and doctors are now required to consider all potential alternatives, including illnesses and accidental injuries, before alleging abuse. In Roberson's case, his attorneys say evidence shows Curtis' symptoms can be attributed to a fall she had from a bed and severe pneumonia, which she had been battling for at least a week before her death and that had progressed to the point of sepsis.

Based on the new research and diagnostic guidelines alone, Roberson asked the TCCA to overturn his conviction and death sentence in 2016. That court ended up staying his execution and ordered an evidentiary hearing based on the updated science. However, the trial court judge who oversaw the hearing denied his request for post-conviction relief, and the TCCA affirmed that decision in January 2023.

Seven months later, Roberson filed a new request for the TCCA to vacate his conviction based on more updated science in abusive head trauma, as well as new evidence, including Curtis' complete autopsy report and brain scans that were uncovered during his previous bid for post-conviction relief.

While that appeal was pending, Moody and several other lawmakers were familiarizing themselves with his case and encouraging their colleagues to look into it as well. Moody he said he can't remember exactly when he learned about Roberson's case, but shortly after doing so, he took a deep dive into it. Harrison and other lawmakers did as well.

Through their research, the lawmakers learned about Andrew Wayne Roark's appeal of his child abuse conviction, which was based on similar shaken-baby-syndrome evidence given by the same expert witness who testified in Roberson's case. Moody said lawmakers were hopeful that both convictions would be overturned based on the junk science law.

On Oct. 9, the TCCA granted Roark's bid for relief. However, less than 24 hours later, the court denied all of Roberson's requests. Soon after that, the Texas Board of Paroles and Pardons also denied Roberson's clemency request, making his Thursday execution appear inevitable.

"We went from thinking everything was tracking correctly to an enormous amount of remedies being taken off the table," Moody told Law360.

That's when the legislative process kicked into high gear. Moody scheduled a hearing about Roberson's case and the bigger issues with the junk science law as soon as legislative procedural rules allowed, and lawmakers began discussing a subpoena.

As the committee voted to issue its subpoena and turned to state courts for help enforcing it, Roberson appealed the TCCA's latest decision to the U.S. Supreme Court, arguing the state court's denial of his request violated his due process rights. He also submitted an emergency request to stay his execution. The Supreme Court issued a denial on both requests Thursday, finding it lacked jurisdiction to review Roberson's case because it was based solely on Texas state law.

It's not clear what will happen to Roberson's case after he testifies Monday — it will revert to a criminal case at that point — but Moody said he and his colleagues will continue to raise awareness about the shortcomings of Texas' criminal justice system.

"Each one of us has a tiny microphone that we can utilize to speak into," he told Law360.

--Editing by Brian Baresch and Lakshna Mehta.

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