THE GUARANTEE OF DUE PROCESS REQUIRES THAT DECISIONMAKING WITHIN THE LEGAL SYSTEM WHICH DEPRIVES A PERSON OF LIBERTY AND PROPERTY MUST BE PROCEDURALLY AND SUBSTANTIVELY CORRECT. PROCEDURAL CORRECTNESS REQUIRES THAT THE PROCESS BY WHICH THE DECISION WAS MADE CONFORM TO PRESCRIBED PROCEDURES. SUBSTANTIVE CORRECTNESS REQUIRES THAT THE BASIS FOR A DECISION BE FIRMLY ROOTED IN EMPIRICAL EVIDENCE. APPELLATE COURTS HAVE TENDED TO EMPHASIZE PROCEDURAL CORRECTNESS AS THE MEASURE OF DUE PROCESS, PRESUMING THAT PROCEDURAL CORRECTNESS GUARANTEES SUBSTANTIVE CORRECTNESS. AN EXAMINATION OF PAROLE DECISIONMAKING REVEALS THE FALLACY IN SUCH AN ASSUMPTION. THE FOLLOWING OF CORRECT PROCEDURES IN DECIDING WHETHER TO GRANT AN INMATE PAROLE DOES NOT ENSURE THAT THE DECISION MADE WILL BE A GOOD ONE. IF THE RATIONALE FOR THE PAROLE SYSTEM ITSELF IS THE SHORTENING OF PRISON SENTENCES FOR OFFENDERS WHO ARE PREDICTED TO BE ABLE TO LIVE IN THE COMMUNITY WITHOUT OFFENDING AGAIN, THEN REJECTION OF PAROLE MUST BE DERIVED FROM AN EMPIRICALLY BASED PREDICTION OF RECIDIVISM. WHEN SUCH DATA ARE NOT THE BASIS FOR PAROLE DECISIONS, THE DUE PROCESS RIGHTS OF THE AFFECTED INMATE HAVE BEEN SUBSTANTIVELY VIOLATED. SENTENCING DECISIONS AND DECISIONS REGARDING INVOLUNTARY COMMITMENT MUST LIKEWISE BE BASED UPON EMPIRICAL EVIDENCE THAT SUPPORTS THE RATIONALE OF THE DECISIONMAKER. ONLY BY FOCUSING UPON THE SUBSTANTIVE NATURE OF DECISIONS CAN THE DUE PROCESS RIGHTS OF CITIZENS BE PROTECTED FROM THE SUBJECTIVITY AND ARBITRARINESS OF DECISIONMAKERS IN THE LEGAL SYSTEM. FOOTNOTES ARE PROVIDED. (RCB)