Police Say Seizing Property Without Trial Helps Keep Crime Down. A New Study Shows They’re Wrong.

In 2015, New Mexico lawmakers unanimously passed a bill to all but end civil asset forfeiture, the process that lets police keep cash or property they seize, even if they never charge the owner with a crime, so long as they suspect that it’s linked to criminal activity. High-profile lawsuits and press attention had prompted some states to reexamine their forfeiture laws.

Law enforcement officials howled in outrage. In New Mexico, sheriffs and prosecutors implored the governor to veto the legislation. Eliminating civil forfeiture, they argued, would hand the bad...