Mizelle was nominated by former President Donald Trump in 2020 at age 33. The American Bar Association said at the time she wasn't qualified because she hadn't been practicing law for long enough.
Lisa Montgomery was scheduled to die by lethal injection on Tuesday, and would be the U.S. government's first execution of a female inmate in more than 67 years.
Esther Salas is calling for reforms to keep judges and other court officials safe from attacks. "This is a matter of life and death," she said. Her son was killed at her home last month.
The judge cites the coronavirus pandemic in blocking the Trump administration's attempt to widen the criteria for what makes an immigrant a "public charge."