In 2005, Kendra’s Law was extended for another five years. In all, more than 8,000 people have been treated under its provisions, and the results have been striking. A 2005 study of more than 2,700 people to whom the law was applied found that, after treatment, the rate of homelessness in the population fell by 74 percent, the number who needed to be rehospitalized dropped by 77 percent and the number arrested fell by 83 percent. And a study published this year found that people receiving treatment under Kendra’s Law were only one-fourth as likely to commit violent acts, had a reduced risk of suicide and were functioning better socially than members of a control group.

It’s hard to imagine a stronger argument for making the law permanent. And yet, as it comes up for renewal this month, the state Office of Mental Health is recommending only a five-year extension. Why the hesitation? Apparently, the Office of Mental Health is ambivalent about its star performer. In its latest five-year Statewide Comprehensive Plan for Mental Health Services, Kendra’s Law is not even mentioned, and the program it supports — assisted outpatient treatment — is referred to briefly only twice.

Perhaps state mental health officials are responding to critics who consider the law politically incorrect because it mandates psychiatric treatment by court order, supposedly violating the patients’ freedom to choose or forgo treatment. But these are people whose illness interferes with their ability to understand that they are sick and need medication. They do not have the choice to live freely and comfortably, but only to be homeless, in jail or in a psychiatric hospital.

The people who could be treated under Kendra’s Law account for only one in 10 seriously ill psychiatric patients. But when these people are untreated, they also make up one-third of the homeless population, and at least 16 percent of the jail and prison population. These people are ubiquitous in city parks, public libraries and train stations. And a small percentage become dangerous, even homicidal.

The law has been a model of success, not only in New York but also in 44 other states that now have similar laws (including, most recently, New Jersey and Maine). Unfortunately, these laws are too rarely used. California, for example, has passed an equivalent to Kendra’s Law known as Laura’s Law, but has not enforced it. If it had, it might have prevented 36-year-old John Patrick Bedell from wandering the country last March, taking orders from his psychotic brain, despite his family’s frantic attempts to get treatment for him. Mr. Bedell ultimately shot two security guards at the Pentagon, and was shot and killed by the officers he injured.

Kendra’s Law saves lives. By keeping patients on medication, it also saves money that might otherwise be spent on rehospitalization, prosecution and incarceration. New York should take lasting advantage of both benefits by making the law permanent.

E. Fuller Torrey, the founder of the Treatment Advocacy Center, is the author of “The Insanity Offense: How America’s Failure to Treat the Seriously Mentally Ill Endangers Its Citizens.”