A new lawsuit filed by the city of San Francisco on behalf of the state of California alleges that over the past five years, the state of Nevada has dumped 1,500 mental patients onto other states by putting them them on Greyhound busses and sending them over state lines with no prior arrangements with families or other mental hospitals once they arrive.

According to the federal class action lawsuit that the city of San Francisco is spearheading, nearly all of the patients bussed to California need continuous medical care—none of which Nevada state arranged, and all of which cost the city of San Francisco at least $500,000.

"While some of the patients were given the names of shelters or told to dial '911' upon arrival in California, a substantial number were not provided any instructions or assistance in finding shelter, continued medical care, or basic necessities in the cities and counties to which they were sent," the formal complaint states.

Rawson-Neal Hospital and its administrators and staff, which include doctors, nurses and social workers, were aware their patients were indigent, living in shelters or on the streets of Las Vegas or other Nevada cities, and suffered from mental illness requiring ongoing medical care and medication, the plaintiff says.

"They understood and expected that the bused patients would rely on San Francisco's public health resources for continuing medical care," the complaint continues. "Nevada, through its political subdivisions, is required by state law to provide 'care, support and relief to the poor, indigent, incompetent, and those incapacitated by age, disease or accident' to county residents."

San Francisco City Attorney Dennis Herrera wrote a letter of protest to Nevada Attorney General Catherine Cortez Masto this past August and warned that he and his state may sue over the egregious denial of responsibility.

"Homeless psychiatric patients are especially vulnerable to the kind of practices Nevada engaged in, and the lawsuit I've filed today is about more than just compensation – it's about accountability," Herrera said in a statement Wednesday. "What the defendants have been doing for years is horribly wrong on two levels: it cruelly victimizes a defenseless population, and punishes jurisdictions for providing health and human services that others won't provide."

Nevada's Chief Deputy Attorney General Linda Anderson sent Herrera a letter on Monday claiming that the Greyhound transfers were, in fact, appropriate considering that, according to the Los Angeles Times, hundreds of California residents had been treated at Rawson-Neal since 2008.

Herrera's public threat to sue Nevada began in August when he cited a Sacramento Bee story in which a schizophrenic patient named Brown said was sent on a 15-hour bus ride to Sacramento, despite never having been there before, having no family or friends to speak of there, and with no prior arrangements for his care, housing or medical treatment.

According to a statement the City Attorney's Office released, the Nevada-run hospital had "discharged Brown in a taxicab to the Greyhound bus station with a one-way ticket to Sacramento, snacks, and a three-day supply of medication to treat his schizophrenia, depression and anxiety. Brown was instructed to call 911 when he arrived. A Rawson- Neal physician reportedly recommended 'sunny California' to Brown as a destination, according to the Sacramento Bee, because they 'have excellent health care and more benefits than you could ever get in Nevada.'"