Governor Kate Brown signed legislation last week making Oregon the first state to enact statewide rent control. One would be hard put to identify an economic policy with a more proven record of destruction. Democrats say the law will ease the state’s housing-affordability crisis, but it will make it worse.

Effective immediately, the law prohibits landlords from raising rent by more than 7% over inflation on non-subsidized buildings, with exemptions for the first 15 years of occupancy. It severely restricts when landlords...