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The Texas Supreme Court weighs whether death row Robert Roberson — whose death sentence was temporarily halted last month — must testify before a Texas House committee before the state can carry out his execution.

The state’s highest civil court temporarily stayed Roberson’s execution last month after the House Criminal Judiciary Committee subpoenaed the man Oct. 16, seeking the 57-year-old Texan convicted of killing his 2-year-old daughter , to testify about his murderer. case at the Texas Capitol four days after his scheduled execution.

That subpoena sparked an unprecedented question about the separation of powers in the state constitution — does the subpoena of legislative members take precedence over the executive’s power to carry out a death sentence, or is it the other way around?

Here’s what you need to know.

(There are conflicting accounts of the Robert Roberson murder case. Here’s what you need to know.)

Background: Roberson was convicted of killing his chronically ill 2-year-old daughter, Nikki Curtis, who Roberson said fell off the bed at the family’s home in Palestine in 2002 before rushing her to the emergency room . A doctor diagnosed her with Nikki shaken baby syndromewhich involves abuse.

Roberson’s attorney did not challenge the diagnosis during the trial, arguing only that Roberson did not intend to kill her daughter. But in the years since the trial, new scientific and medical evidence emerged showing that symptoms associated with shaken baby syndrome could also indicate naturally occurring medical conditions.

In several appeals over the past two decades, experts have presented evidence that Nikki had undiagnosed pneumonia in the days before her fall and that it progressed to sepsis and suppressed her breathing. She was also prescribed medication that was no longer given to infants.

During a recent legislative hearing, a juror in Roberson’s trial said he would not have convicted Roberson if he had been shown all of Nikki’s medical records, including a CT scan and toxicology report. Meanwhile, Gov. Greg Abbott and Attorney General Ken Paxton I argue that Roberson is guilty and that the case has already been properly tried.

Why the Texas House committee sued: Commission members say they called Roberson to testify after hearing expert testimony about Texas’ 2013 junk science law, which allows courts to overturn a conviction when the scientific evidence at the heart of the case has been discredited. Roberson tried unsuccessfully to use the law to win a new trial.

After the House committee issued the subpoena, they obtained a temporary restraining order from a Travis County civil court to stop Roberson’s execution. Paxton then filed a petition with the Court of Criminal Appeals on behalf of the TDCJ, asking the state’s highest criminal court to overturn that decision because the civil court lacked jurisdiction over the matter. The appeals court ruled in favor of Paxton.

But the House committee responded by filing an emergency motion with the Texas Supreme Court, the state’s highest civil court. The House argued that the Court of Criminal Appeals lacked jurisdiction over the case because a subpoena is a civil matter. The Supreme Court issued a temporary stay of execution and required each side to provide legal documents before issuing a final ruling.

What the state says: Paxton argues that the court’s order to force the state to stay a statutorily imposed criminal conviction “inhibits the separation of powers.”

“The relief sought by the House Committee here usurps the Governor’s exclusive prerogative to grant a thirty-day reprieve in a capital case,” Paxton’s office wrote in a legal brief. “The Constitution’s specific grants of authority to the CCA and the governor with respect to criminal convictions and temporary stays, respectively, thus necessarily exceed any general subpoena power.”

What the House committee says: Lawmakers, including committee chairman Joe Moody, D-El Paso, and committee member Jeff Leach, R-Plano, say Paxton’s office prevented the TDCJ from honoring the subpoena and letting Roberson testify. They say issuing the subpoena did not assume the powers of another branch because Roberson’s execution was only temporarily halted and lawmakers have the right to hear testimony to inform policymaking.

“Given the dispute over some of the facts in Roberson’s case, the Committee found it essential to hear him in person to judge his credibility as a witness,” the House members argued in a brief legal brief.

Wider impact: The state supreme court’s decision in the case is unlikely to have a direct impact on whether or not Roberson is granted a new trial, since that decision would be made by a criminal court. But it could have repercussions on the subpoena power of the Legislature. And a death row inmate’s testimony at the state Capitol about his case would be historic.

In January, three of the five Court of Criminal Appeals judges who allowed Roberson’s execution to move forward will no longer be on the court. If Roberson’s case somehow ends up back before that court and any of the new justices take a different position, the votes could swing in Roberson’s favor.

The court’s decision will also answer a novel legal question about whether a subpoena or enforcement order takes precedence.

“I think what we’re seeing are checks and balances of the different branches of government, which is what the constitutional vision has been in the United States and has been largely replicated in Texas,” said Marc Levin, chief policy adviser at to the Council for Criminal Justice. “It’s healthy for that to happen.”