Revealed: drug tests in California prisons yielded false positives, affecting thousands of people

Incarcerated women at Central California Women’s Facility in Chowchilla are among thousands affected by false positives. Composite: Los Angeles Times, Smith Collection/Gado, Getty Images

Thousands of drug tests used by a major US diagnostic company in California prisons last year are suspected to have generated false positive results, an enormous error that has jeopardized the parole requests of some incarcerated people, according to civil rights lawyers and prison medical records.

California prison officials have known about the issue for months, but have failed to clear people’s records or reverse the consequences people have faced from the tests.