PATUXENT WAS ESTABLISHED UNDER A 1951 MARYLAND STATUTE CALLING FOR A SPECIAL FACILITY TO HOUSE 'DEFECTIVE DELINQUENTS' -- DEFINED AS INDIVIDUALS WHO EVIDENCED 'PERSISTENT AGGRAVATED ANTISOCIAL OR CRIMINAL BEHAVIOR' SO AS TO BE AN 'ACTUAL DANGER TO SOCIETY.' THERE WERE SEVERAL CONCEPTS UNDERLYING THE LAW: THAT THERE EXISTED A DEFINABLE SUBPOPULATION OF MENTALLY DISTURBED (BUT NONPSYCHOTIC) CRIMINALS; THAT DANGEROUS ONES SHOULD BE PUT AWAY UNTIL SUCH TIME AS THEY NO LONGER WERE DANGEROUS; AND THAT THE BEST WAY TO INDUCE THEM TO CHANGE WAS TO PUT THEM IN A COMBINED PRISON-HOSPITAL SETTING THAT MADE AVAILABLE THE WISDOM OF MODERN PSYCHIATRY. THE PRISON IS FOUNDED ON A SIMPLE FORM OF BEHAVIOR MODIFICATION -- A GRADUATED TIER SYSTEM THROUGH WHICH PATIENTS MUST PASS BEFORE THEY CAN BE RELEASED. TIER ONE IS MADE UP OF STARK PRISON CELLS. IN THE NEXT THREE TIERS RESIDENTS HAVE GRADUALLY INCREASED PRIVILEGES AND POSSESSIONS. RESIDENTS ARE ASSIGNED TO FOUR UNITS (WHICH CUT ACROSS THE TIER SYSTEM), WITH EACH UNIT BEING OVERSEEN BY A TEAM COMPOSED OF SEVERAL PSYCHIATRISTS AND SOCIAL WORKERS. EACH PRISONER IS IN CONTINUOUS CONTACT WITH THE SAME TEAM AS HE WORKS HIS WAY THROUGH THE PROGRAM. THE PROGRAM COMBINES EDUCATION, VOCATIONAL TRAINING, AND THERAPY. THE SUCCESSFUL PRISONER EVENTUALLY ENDS UP AT THE 'PRERELEASE' CENTER, A SEPARATE BUILDING ON THE GROUNDS. IT IS NOTED THAT WHAT MAKES THE PATUXENT PROGRAM UNIQUE IS THE EMPHASIS ON STRUCTURING THE ENTIRE MILIEU TO REINFORCE POSITIVE BEHAVIOR. CONSIDERED AN ADVANCED MODEL FOR REHABILITATING DANGEROUS, HARD-CORE CRIMINALS AT THE TIME OF ITS FOUNDING, THE TIDE TURNED IN THE LATE 1960'S AS CIVIL LIBERTARIANS ATTACKED THE MEDICAL MODEL, PARTICULARLY THE INDETERMINATE SENTENCE THAT GAVE PATUXENT ITS UNIQUE LEVERAGE OVER ITS INMATES. IN A MAJOR REVISION OF THE PATUXENT MANDATE, THE 1977 MARYLAND LEGISLATURE DEFUSED THE CONTROVERSY BY ABOLISHING THE INDETERMINATE SENTENCE AND ELIMINATING INVOLUNTARY COMMITMENT TO THE INSTITUTION. IN 1976, AN INDEPENDENT CONSULTING FIRM EVALUATED PATUXENT AND PRONOUNCED IT RELATIVELY INEFFECTIVE IN REDUCING RECIDIVISM, ALTHOUGH THE PATUXENT STAFF STILL CLAIMS A 37 PERCENT RECIDIVISM RATE, COMPARED WITH ABOUT 60 PERCENT IN OTHER STATE PRISONS. THE COST EFFECTIVENESS OF PATUXENT CONTINUES AS A SOURCE OF CONTROVERSY, BUT IN THE ABSENCE OF OTHER PROVEN ALTERNATIVES FOR THE REHABILITATION OF HARDENED CRIMINALS, THERE IS A RELUCTANCE TO ABOLISH ITS PROGRAM. (RCB)