Yes, Virginia, Kendra's Law works ...

From the Washington Post December 30, 2007:

Susan Wezel had been committed to the city's hospital wards more than a dozen times in 10 years. Her psychosis was so deep and debilitating that she lost her career and her relationship with her son, as she refused to take her medication or follow treatment.

But because of a New York state law, Wezel hasn't been hospitalized in more than a year. She doesn't wander the streets alone at night anymore. She takes her medication willingly. She even has plans to follow her dream of singing at a neighborhood nightspot, something that was unthinkable 18 months ago.

Wezel and her caseworker agree that the transformation occurred because of the law, which allowed officials to force Wezel into an outpatient treatment program after she was discharged from a hospital.