How New York Practices Solitary Confinement "Rethinking Solitary Confinement" (front page, March 11) reports on the Mississippi prisons" drastic reduction in the use of solitary confinement. Similar successful efforts are under way in other states, including Maine and Colorado. In contrast, New York City is going backward: the Department of Correction is carrying out a drastic increase in solitary confinement cells (pretrial detainees held in 23-hour lock-in, with only an hour a day for exercise and showers). The jail population has been falling for years, yet the department plans an expansion that will give New York City one of the highest rates of punitive segregation in the country. New York City's jails - notoriously chaotic, unruly and brutal - need reform, but simply locking up more and more prisoners is not the solution. New York should follow Mississippi's lead. The writers are, respectively, staff attorney and director of the Prisoners" Rights Project of the Legal Aid Society.