District Judge Steven Boyce made the ruling on Thursday, which will sever the defendants' cases, according to East Idaho News.
The couple was previously being tried together on multiple counts of first-degree murder and conspiracy to commit murder in the deaths of Ms Vallow's children, 7-year-old Joshua Vallow and 16-year-old Tylee Ryan, as well as the death of Mr Daybell's previous wife, Tammy Daybell.
The decision to separate the cases comes on the heels of new DNA testing, which included all parties allegedly involved with the crime. The test results were returned too close to the 3 April trial date for both the defence attorneys to adequately review. The proximity of the results to the trial date, along with Ms Vallow's refusal to waive her right to a speedy trial, forced Mr Boyce to separate the cases.
Mr Daybell's case will be rescheduled, but Ms Vallow's will continue as planned.
“I have to balance these rights of these defendants in this case,” Judge Boyce said. “Severance is the only option I see.”
He said that Mr Daybell's trial could be pushed back beyond six months.
“The length of the delay, if I were to continue this, it would be up to Ada County and I don’t believe it could be a short delay,” he said. “It would have to be more than six months additionally.”
Both defendants have pleaded not guilty to all charges.
The new DNA testing resulted from hair being found at the crime scene. John Prior, Mr Daybell's attorney, said the discovery was important new evidence and insisted its inclusion in the case was vital to ensure a fair trial.
“That evidence provides, at least from my perspective, an explanation potentially of where Mr. Daybell and I are going to go in this particular case,” Mr Prior said. “I need to have an opportunity to test that evidence.”
Jim Archibald, Ms Vallow's attorney, agreed with Mr Prior's argument.
“If my client waived her speedy trial, I would also be asking for extra time. But since she has held that right and held it close to her,” he said. “I have to respect that constitutional autonomy that she has.”