Momentum is building in a case regarding homeless encampments that will be argued before the U.S. Supreme Court next month and could have major implications for cities as homelessness nationwide has reached record highs.

Dozens of briefs have been filed in recent days, including from the Department of Justice, members of Congress and state attorneys general. They joined the growing number of western state and local officials who have submitted briefs urging the justices to overturn a controversial lower court decision they say has prevented them from addressing homeless encampments.

In 2018, the 9th U.S. Circuit Court of Appeals — whose jurisdiction includes nine Western states — ruled it was unconstitutional to punish people who are “involuntarily homeless” for sleeping outside if there are not enough shelter beds. Its Martin v. Boise decision found that doing so would violate the cruel and unusual punishment clause of the Eighth Amendment to the U.S. Constitution.

Social justice advocates have long supported the decision based on the belief that homelessness shouldn’t be criminalized, although rights groups such as the American Civil Liberties Union have yet to file briefs in the case. Many officials in the West, on the other hand, say the decision has prevented them from managing a surge in encampments on sidewalks, in parks and other public places.

The U.S. experienced a dramatic 12% increase in homelessness last year to its highest reported level, a federal report found, as soaring rents and a decline in coronavirus pandemic assistance combined to put housing out of reach for more Americans. About 653,000 people were homeless in the January 2023 count, the most since the country began using the yearly point-in-time survey in 2007.

More than half the people experiencing homelessness in the country were in four states: California and Washington, which are both under the 9th Circuit’s jurisdiction, along with New York and Florida. About 28% of the nation’s homeless are estimated to be in California alone, according to the federal report from the Department of Housing and Urban Development.