A lab technician runs tests on a drug for COVID at Neolpharma in Caguas, Puerto Rico. The territory exports $50 billion of biopharmaceuticals, making it the largest exporter in the U.S.
California – Thousands of incarcerated people in California may have received false positive drug test results last year due to a testing error by Quest Diagnostics, raising serious concerns over parole denials and the use of flawed evidence in life-altering decisions.
Between April and July 2023, Quest Diagnostics, the state’s sole contracted drug testing provider for prisons, temporarily used an “alternative” reagent for urine-based opiate tests amid a supply shortage of its regular chemical. The switch caused a spike in positive test results—jumping from a 6.6–6.8% rate earlier in the year to 17.1% in May, 20.5% in June, and again 17.1% in July, according to state records reviewed by the nonprofit UnCommon Law.
When Quest resumed use of its original reagent in August, the positive test rate immediately dropped back to its historical average of 6.8%.
Although California prison officials were made aware of the issue months ago, civil rights attorneys say the state has not cleared people’s records or adequately addressed the consequences these flawed tests have caused. Some incarcerated people have faced parole denials due in part to these results—despite the tests not being followed by confirmatory testing or interpreted by medical providers.
Alison Hardy, an attorney with the Prison Law Office (PLO), said prison health officials acknowledged that roughly 6,000 people may have been affected. A separate analysis by UnCommon Law estimated over 5,000 of those test results could be false positives.
“These tests are basically worthless,” said Dr. Fred Rottnek, an addiction expert who reviewed the data. He called for a full review of how these test results may have influenced parole decisions and medical care.
One UnCommon Law client—a man in his 60s incarcerated since his teens—was denied an expedited parole review after two positive drug tests in May and July 2023. His doctor confirmed those tests were done during the period Quest used the alternative reagent and expressed confidence that the man had not relapsed. Still, the Board of Parole Hearings (BPH) cited the tests as evidence of “continued substance abuse” and denied him early consideration.
Attorneys argue the tests were unreliable and never confirmed, yet were still used by the BPH in parole decisions. “These drug tests, if they remain uncorrected, hugely alter the picture,” said attorney Lilli Paratore.
Quest confirmed the alternate reagent was FDA-cleared, but acknowledged it led to a higher presumptive positivity rate. The company said confirmatory testing is available but must be specifically requested—a step prison healthcare often does not take.
UnCommon Law and other advocates are now calling for the state to wipe the false positives from prisoners’ records and provide clear remedies for those affected.
“The board’s behavior here is lazy, reckless, and irresponsible,” said UnCommon Law executive director Keith Wattley. “It has devastating consequences for incarcerated people and their families.”
