AWALK THROUGH downtown Washington will invariably take you past one or more haggard and homeless people who are obviously mentally ill. Some 1,500 to 2,000 of these men and women now live on the city's streets and in its homeless shelters. The advocates who fought vigorously for the freedom of former patients blame mental health systems that have been distressingly slow in developing community-based mental health care. State and local governments blame advocates for forcing deinstitutionalization faster than comprehensive outpatient care can be set up.

Both sides are partially responsible for the 100,000 former mental patients across the country who are homeless and without regular care. In this city and elsewhere, the people who know this best are the shelter providers. They watch the victories by civil libertarians, knowing that more former mental patients will turn up at their doors. They listen to local governments' claims of improved community-based care, knowing that the mentally ill people whom they harbor still face crisis. Even when community-based care is available, the former patient now has the right to refuse it. Perhaps it's time to try a different approach.

The American Psychiatric Association has called for permitting "brief" periods of involuntary confinement and treatment, but only when a former mental patient is 1) out of control and irrational, 2) incompetent to make medical decisions and 3) obviously suffering. That could help prevent the tragic situation in which a former patient's health slowly deteriorates while he is living on the streets.

Lawyers could still represent the interests of a homeless person who was back -- briefly -- in a hospital. But meanwhile the mental health system would be providing the care and medication needed to enable that person to be released again and to live with some degree of independence. Shelter providers could be better incorporated into the care system. Is this feasible? A walk through the streets and the shelters shows that the legal ''victories'' haven't stopped the suffering of the chronically mentally ill. There has to be room for a new approac