The case is considered the most significant to come before the high court in decades on homelessness, which has reached record levels in the United States.

In California and other Western states, courts have ruled that it’s unconstitutional to fine and arrest people sleeping in homeless encampments if shelter space is lacking.

A cross-section of Democratic and Republican officials contend that makes it difficult for them to manage encampments, which can have dangerous and unsanitary living conditions.

But hundreds of advocacy groups argue that allowing cities to punish people who need a place to sleep will criminalize homelessness and ultimately make the crisis worse as the cost of housing increases.

Dozens of demonstrators gathered outside the court Monday morning with silver thermal blankets and signs like “housing not handcuffs.”

The Justice Department has also weighed in. It argues people shouldn’t be punished just for sleeping outside, but only if there’s a determination they truly have nowhere else to go.

The case comes from the rural Oregon town of Grants Pass, which started fining people $295 for sleeping outside to manage homeless encampments that sprung up in the city’s public parks as the cost of housing escalated.

The measure was largely struck down by the San Francisco-based 9th Circuit Court of Appeals, which also found in 2018 that such bans violated the Eighth Amendment by punishing people for something they don’t have control over. The 9th Circuit oversees nine Western states, including California, which is home to about one-third of the nation’s homeless population.

The case comes after homelessness in the United States grew a dramatic 12%, to its highest reported level as soaring rents and a decline in coronavirus pandemic assistance combined to put housing out of reach for more Americans, according to federal data. The court is expected to decide the case by the end of June.