Citing an affordable housing crisis of “epic proportions,” the California Supreme Court made it easier Monday for cities and counties to require developers to sell some housing at below-market rates.

The unanimous decision, written by Chief Justice Tani Cantil-Sakauye, follows study after study documenting a lack of affordable housing in the state, especially in California’s coastal regions....

The decision clears the way for Los Angeles and other cities to require developers to sell a percentage of the units they build at below-market rates as a condition of a building permit. Developers also could be given the option of paying into a fund for low-cost housing.

“I applaud the California Supreme Court’s decision,” Los Angeles Mayor Eric Garcetti said in a statement. “This gives Los Angeles and other local governments another possible tool to use as we tackle our affordable housing crisis.”