Gov. Tim Walz signed a law prohibiting training for licensed police officers on "excited delirium," making Minnesota at least the third state to ban a diagnosis that national medical associations have rejected as pseudoscience.

Excited delirium usually refers to a person possessed by a potentially deadly form of agitation, sometimes abetted by drug abuse, and displaying aggressive behavior, profuse sweating, public nudity, mouth foaming and superhuman strength. The term is often invoked by law enforcement after a person dies in custody — including in the killing of George Floyd — and in recent years it's been criticized as an overly broad umbrella term used to justify deadly policing tactics.

In 2021, following the killing of Floyd and Elijah McClain in Colorado, the American Medical Association released a statement opposing the diagnosis as "a manifestation of systemic racism." The American Psychiatric Association followed with a similar rejection, and the National Association of Medical Examiners now says it should never be cited as a cause of death.

"Right now, there's not a single medical association that upholds excited delirium as legitimate," said Dr. Altaf Saadi, a neurologist at Massachusetts General Hospital who has called for the end of the term's use in the United States, in an interview in May.

In introducing the bill, Rep. Jessica Hanson, DFL-Burnsville, described excited delirium as a diagnosis "rooted in anti-Black racism" in a committee hearing in April.

"It has no basis in science, no functional meaning in medicine and no clear diagnostic criteria nor symptomatology," said Hanson.

Walz signed the bill May 24 and it went into effect the next day.

Since October, Colorado and California have passed laws prohibiting its use among emergency responders, and more state legislatures, including Hawaii, have proposed similar laws. Mayor Jacob Frey banned training on excited delirium for the Minneapolis Police Department several years ago. Minnesota's largest police professional association took no position on the bill.

In 2019, McClain died after police in Aurora, Colo., restrained him in a chokehold and paramedics injected him with an overdose of the sedative ketamine. The 23-year-old Black man was walking home after buying iced tea, apparently dancing to music on his headphones, when a neighbor called 911 to report he was acting "sketchy." Afterward, the paramedics, who have since been convicted of criminal negligence, said they believed McClain was suffering from excited delirium.

The next year, Minneapolis police officer Derek Chauvin killed Floyd by kneeling on his neck. In a federal civil rights trial, three officers convicted in Floyd's death testified extensively that they believed Floyd may have been suffering from excited delirium. Officer Alex Kueng said he believed the condition could cause Floyd to "spring back to life" and become a threat again, even after he was unresponsive. In a separate trial, Chauvin's attorney argued his client was acting as a "reasonable police officer" watching for signs of excited delirium.

In previous Minneapolis Police Department training, officers were told that excited delirium was an extreme form of agitation that manifests as superhuman strength, bizarre speech and aggressive conduct. A training slideshow, shown to the jury, featured an image of officers subduing a man by pinning him with their knees, similar to how Chauvin pinned Floyd. Officer Thomas Lane, who mentioned excited delirium on the scene, said he was taught to restrain people in such condition in order to "keep a person from thrashing, hold them in place."