The homeless crisis in America is set to come to a head with a Supreme Court ruling as early as this spring, in the case of Johnson v. City of Grants Pass, Oregon.

The Supreme Court could—depending on what it decides—force changes in city ordinances and homeless policies across the country.

The decision is one of the most anticipated in years for San Francisco and other cities facing legal challenges from homeless people and advocacy groups.

At the heart of the case is the challenge by three homeless people to ordinances in the Oregon town of Grants Pass that prohibit homeless people “from using a blanket, pillow, or cardboard box for protection from the elements.”

The U.S. Court of Appeals for the Ninth Circuit, drawing on logic applied in the 2018 decision in Martin v. City of Boise, sided with the plaintiffs and blocked Grants Pass from enforcing its ordinance in the absence of shelters or other accommodations for the homeless.

The decision applies across nine western states, Alaska, Arizona, California, Hawaii, Idaho, Montana, Nevada, Oregon, and Washington.