A state appeals court has reversed the 2016 second-degree murder conviction of a 28-year-old woman accused of causing a fatal accident in Tuolumne County while driving under the influence of drugs.

In an opinion released on Wednesday, the Fifth District Court of Appeal ruled that a Tuolumne County Superior Court judge had wrongly denied a full hearing to determine the validity of results from a blood test used as evidence in the trial of Brenda Estefania Barrera, of Sunnyvale.

The decision means that, barring a reversal of the appeals court ruling by the California Supreme Court, the case will go back to Tuolumne County for retrial.

“Words cannot express our excitement,” said Deputy Public Defender Hallie Gorman, who represented Barrera at trial with Deputy Public Defender Dana Gross.

Gorman declined to comment further on the ruling because she said not enough is known at this time. She and Gross would likely represent Barrera if the case is sent back to Tuolumne County for retrial.

Assistant District Attorney Eric Hovatter, who prosecuted the case at trial, did not respond to a request for comment Thursday.

Barrera was found guilty by a jury of second-degree murder and driving while under the influence causing great bodily injury in March 2016 following a six-day trial.

Superior Court Presiding Judge Donald Segerstrom presided over the trial and sentenced Barrera to 28 years to life in prison on May 20, 2016. She’s incarcerated at Central California Women’s Facility in Chowchilla.

The charges stemmed from a two-car collision in April 2015 on Highway 108 near J59 that resulted in the death of Maxsimiano Aldana, 78, of Escalon, and sent four others to the hospital with major injuries.

Barrera, then 24, was driving west on Highway 108 in a 2005 Mercedes Kompressor at about 10 a.m. on April 21, 2015, when she drifted into the opposing lane about a mile from J59 and collided with a 2005 Chevy Malibu driven by Aldana.

Aldana was pronounced dead at the scene by emergency responders. His three passengers, which induded his 69-year-old wife and two other people in their 80s, were taken by helicopter to hospital in Modesto with numerous broken bones.

A 21-year-old passenger in Barrera’s car was also flown to a Modesto hospital for treatment of major injuries.

Barrera, who was driving home from Black Oak Casino Resort, had a suspended license for a prior DUI conviction in 2014.

As part of the prior conviction, Barrera had signed an advisement that warned she could be charged with murder if she killed someone while driving under the influence of alcohol, drugs, or both.

The reversal of Barrera’s conviction hinged on the testimony given at trial by John Lopez, a criminalist from the Department of Justice, who analyzed blood drawn from Barrera at 12:40 p.m. on the day of the accident.

Lopez testified that he had conducted an analysis to determine the level of THC, the active ingredient in marijuana, that was in Barrera’s system and believed she had consumed marijuana within three hours of her blood being drawn.

However, the laboratory Lopez worked for had suspended the reporting of specific THC levels in early 2015 after finding previously tested samples that exceeded the maximum margin of error.

The defense’s expert, Okorie Okorocha, testified at trial that Lopez’s opinion was “completely unsupportable” and that the evidence could only suggest that Barrera used marijuana within two weeks of her blood being drawn.

Lopez’s opinion that Barrera had a “high quantity of THC” in her blood at the time was wrongfully allowed by the trial court without a hearing to determine whether the test results were valid, according to the appeals court opinion.

“The People were required to establish that correct procedures had been used, but the trial court refused to conduct a full evidentiary hearing to determine whether correct procedures had been used,” the opinion stated. “The People never established whether Lopez could rely on the quantity of THC in Barrera’s blood.”

In a 2016 press release following Barrera’s conviction, the Tuolumne County District Attorney’s Office stated that the evidence pointing to her conviction was “strong” — as opposed to a lesser charge — because of the advisement she had signed after the DUI in 2014.

The appeals court ruled in its opinion that without the evidence presented at trial to the amount of THC in Barrera’s blood, it could not say that the jury would inevitably find her guilty of second-degree murder.

Barrera was represented during the appeals process by Sacramento attorney Scott Cameron, who declined to comment on the opinion.

According to the Central California Appellate Program, the Attorney General’s Office can petition the appeals court to reconsider the reversal of Barrera’s conviction within 15 days of the opinion being issued.

The reversal can also be appealed to the California Supreme Court no earlier than 30 days and not later than 40 days after the opinion is issued.

The Attorney General’s Office did not respond to a request for comment Thursday afternoon.

Contact Alex MacLean at amaclean@uniondemocrat.com or (209) 588-4530.