Acadia Healthcare is one of America’s largest chains of psychiatric hospitals. Since the pandemic exacerbated a national mental health crisis, the company’s revenue has soared. Its stock price has more than doubled.

But a New York Times investigation found that some of that success was built on a disturbing practice: Acadia has lured patients into its facilities and held them against their will, even when detaining them was not medically necessary.

In at least 12 of the 19 states where Acadia operates psychiatric hospitals, dozens of patients, employees and police officers have alerted the authorities that the company was detaining people in ways that violated the law, according to records reviewed by The Times. In some cases, judges have intervened to force Acadia to release patients.

Some patients arrived at emergency rooms seeking routine mental health care, only to find themselves sent to Acadia facilities and locked in.

A social worker spent six days inside an Acadia hospital in Florida after she tried to get her bipolar medications adjusted. A woman who works at a children’s hospital was held for seven days after she showed up at an Acadia facility in Indiana looking for therapy. And after police officers raided an Acadia hospital in Georgia, 16 patients told investigators that they had been kept there “with no excuses or valid reason,” according to a police report.

Acadia held all of them under laws meant for people who pose an imminent threat to themselves or others. But none of the patients appeared to have met that legal standard, according to records and interviews.