The Washington Supreme Court has unanimously ruled that the state's constitutional right to travel does not include the right to live in a vehicle parked on public property.

Advocates for the homeless slammed the ruling, which now sends the lawsuit filed by a homeless man back to the Ninth Circuit Court of Appeals for review.

"The ruling, which allows for the arrest, fining, and impounding of vehicles of those simply trying to survive, is not only inhumane but exacerbates homelessness," Antonia Fasanelli, executive director of the National Homelessness Law Center, said in a statement to Fox News Digital.

RVs parked in Seattle

RVs and tents along a two-block stretch in Seattle, Washington, on July 22, 2022. (Melina Mara/The Washington Post via Getty Images)

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The case is among the first court battles decided since the U.S. Supreme Court ruled that cities may ban people from sleeping outside.

The legal battle began in 2019 when the city of Lacey passed an ordinance banning RVs and other large vehicles from parking on the street or in lots for more than four hours per day. Violations were punishable by a $35 fine and impoundment of the vehicle, according to the court decision released last week.

The law included a process for visitors to get a permit to park longer in designated areas so long as the requester is "actively engaged with social services," the justices noted in their 13-page ruling.

Authorities ordered Jack Potter, a veteran who had been living in the Lacey City Hall parking lot, to move his truck and 23-foot travel trailer. He obliged, moving to nearby Olympia, the state's capital city.

But the next year he sued the city, invoking the Washington state constitutional right to intrastate travel, which he further argued includes the "right to reside."

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Sign reading "Do not tow my home" on windshield of RV

Notices inform people living in an RV in Seattle of an upcoming homeless camp sweep in this July 2022 file photo. (Melina Mara/The Washington Post via Getty Images)

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"The right to travel includes the right to reside, to stay where one is," the ACLU of Washington wrote in an amicus brief last year.

The brief argued that the city's ordinance amounted to "banishment of people whom Lacey public officials deem undesirable." 

The city argued the law fell squarely within its right to regulate parking, and that it applied to everyone in Lacey equally.

The state supreme court agreed, writing, "Potter has failed to show that Lacey’s parking ordinance violates his asserted state constitutional right to reside in the manner that he has chosen."

"This backwards approach aligns with last month’s similarly harsh Johnson v. Grants Pass ruling by the U.S. Supreme Court, which says that lawmakers can punish people for having nowhere to sleep with fines and jail time," Fasanelli said.

The law center called on the Biden administration and Congress to invest hundreds of billions in rental assistance, public housing and other homelessness prevention services, arguing the "richest country in the world" can afford such services.

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Potter's case will now go to the Ninth Circuit Court of Appeals, which will decide whether Lacey's ordinance runs afoul of the federal right to travel or the Fourth Amendment's protections against government seizures, The Seattle Times reported.

Lacey city officials declined to comment on the ongoing case.

Potter's attorney did not immediately respond to a request for comment.