ALTHOUGH DECRIMINALIZATION HAS BEEN USED TO DESCRIBE LEGISLATIVE REFORMS RELATED TO THE REGULATION OF MARIJUANA, LEGISLATORS AND CRIMINAL JUSTICE PERSONNEL DO NOT SHARE A COMMON CONCEPTION OF WHAT DECRIMINALIZATION MEANS. THE TERM 'DECRIMINALIZATION' IS USED TO REFER TO A THRESHOLD CONCEPT RATHER THAN A DEFINITIONAL CONCEPT, WHERE DECRIMINALIZATION MEANS ANY STATUTORY SCHEME UNDER WHICH THE LEAST SERIOUS MARIJUANA-RELATED BEHAVIOR IS NOT PUNISHABLE BY INCARCERATION. INCARCERATION IS A USEFUL THRESHOLD DEVICE FOR SEVERAL REASONS: IT ELIMINATES THE POSSIBILITY OF IMPRISONMENT, AND ITS ATTENDANT SOCIAL STIGMA REFLECTS A SIGNIFICANT CHANGE IN OFFICIAL ATTITUDES TOWARD MARIJUANA OFFENSES; IT DISTINGUISHES TOTAL CONFINEMENT FROM OTHER LEGAL SANCTIONS; AND IT SUGGESTS OR REQUIRES LESS SEVERE AND LESS ELABORATE CRIMINAL PROCESSES. LEGISLATORS MUST DETERMINE WHAT BEHAVIOR SHOULD BE DECRIMINALIZED AND WHAT RESIDUAL SANCTIONS, IF ANY, SHOULD BE RETAINED TO IMPLEMENT THE STATE'S INTEREST IN DISCOURAGING DECRIMINALIZED BEHAVIOR. LEGISLATIVE OPTIONS FOR DEFINING DECRIMINALIZED OR LEAST SERIOUS MARIJUANA-RELATED BEHAVIOR ENCOMPASS POSSESSORY CONDUCT (STATUTORY RELATIONSHIPS BETWEEN INTENT AND AMOUNT, DESIGNATING THE AMOUNT, AND VARIABILITY IN THE POTENCY OF MARIJUANA), DISTRIBUTIVE CONDUCT, AND THE CULTIVATION OF MARIJUANA FOR PERSONAL USE. A THEORETICAL CONTEXT FOR SELECTING SANCTIONS APPROPRIATE TO MARIJUANA USERS IS PRESENTED (LEGAL SANCTIONS, ARREST AND CONVICTION, IMPOSITION OF NONCRIMINAL SANCTIONS, WHETHER PENALTIES SHOULD BE INCREASED FOR SUBSEQUENT OFFENSES, AND WHETHER A DISTINCTION SHOULD BE MADE BETWEEN JUVENILE AND ADULT MARIJUANA USERS). DETECTION AND POSTARREST CONSEQUENCES OF MODIFYING THE CRIMINAL PROCESS REGARDING MARIJUANA USE ARE DISCUSSED, WITH ATTENTION GIVEN TO CUSTODY AFTER ARREST, COURT APPEARANCE, AND THE ADJUDICATORY PROCESS. THREE CONCLUSIONS ARE REACHED: (1) CRIMINAL PENALTIES SHOULD BE WITHDRAWN FROM ALL BEHAVIOR THAT IS CLEARLY CONSUMPTION-RELATED RATHER THAN SOME MORE RESTRICTIVE CATEGORY OF CONDUCT; (2) NO RESIDUAL SANCTIONS SHOULD BE IMPOSED ON DECRIMINALIZED BEHAVIOR; AND (3) IF RESIDUAL SANCTIONS ARE IMPOSED, THEY SHOULD BE SUMMARILY ADMINISTERED CIVIL FINES. CASE LAW IS CITED, AND FOOTNOTES AND TABULAR DATA ON STATE DRUG LAWS ARE INCLUDED. (DEP)