Street psychiatry offers a radical solution: that for the most acutely mentally ill, psychiatric medication given outdoors could be a critical step toward housing. Dr. Rab, a medical director of Los Angeles County’s Homeless Outreach & Mobile Engagement program, describes the system his team has built as an outdoor hospital, or sometimes as a “DoorDash for meds.”

Every weekday morning, 18 teams fan out across the county, making rounds with about 1,700 patients in tents and vehicles and alleyways. The teams try to persuade them to accept medication, sometimes in an injectable form that remains in the bloodstream for weeks. If clients say no, the teams return, sometimes for months, until they say yes; if they still refuse, the team can petition a court to order involuntary treatment.

This is a major departure for the field of psychiatry, which long discouraged clinicians from tracking down patients in the chaotic conditions where they live. It alarms patients’ rights activists, who say people living on the street may not be in a position to give consent. And critics question whether state resources should go to expensive curbside medical treatment when what people really need is housing.

Over the years that followed, Dr. Jones’s Skid Row experiment has expanded into one of the largest street psychiatry efforts in the nation. Last year, the HOME team doubled in size and was allocated a budget of $43 million. It deploys 223 full time staff members, including 10 psychiatrists, eight psychiatric nurse-practitioners and a clinical pharmacist. This summer, the team started mobile phlebotomy laboratories, which allow staff members to perform blood tests on the spot. Of the 1,919 people the team served last year, 22 percent ended the year housed; around 10 percent were treated involuntarily.