Fentanyl is a synthetic opioid that’s 50-100 times stronger than the pain reliever morphine. While some people use fentanyl on purpose, many others get it in their systems without their knowledge.

This week, Republican Gov. Tate Reeves signed a bill decriminalizing fentanyl test strips in Mississippi, legislation that he said “will help save lives.” It’s the latest in a wave of states taking ...