NCJ Number
43265
Date Published
1977
Length
19 pages
Annotation
MODELS OF JURY VERDICTS INDICATE: THE PROBABILITY OF A 12-MEMBER JURY CONVICTING AN INNOCENT PERSON IS .0221 AND OF ACQUITTING A GUILTY PERSON .0615; FOR A 6-MEMBER JURY, THE FIGURES ARE .0325 AND .1395 RESPECTIVELY.
Abstract
FOLLOWING A REVIEW OF THE LITERATURE STUDYING JURY BEHAVIOR, WHICH DATES BACK TO THE 19TH CENTURY, THE SOCIOLOGICAL AND PSYCHOLOGICAL ARGUMENTS SUPPORTING THE EXISTENCE OF THE EFFECT OF SIZE ARE EXAMINED. VARIOUS STUDIES OF GROUP DYNAMICS HAVE SHOWN THAT: IN SMALL GROUPS EVEN VERY WEAK INTERACTION AMONG MEMBERS PRODUCES SOME COERCIVE EFFECT; THE MORE COMPLEX THE PROBLEM, THE GREATER THE TENDECY TO CONFORM; AND IF THE GROUP IS REQUIRED TO REACH A UNANIMOUS DECISION, THE MINORITY RESPONDS BY MORE WILLINGLY CHANGING SIDES. MOREOVER, FOR A HUNG JURY TO RESULT, A SUBSTANTIAL MINORITY MUST BE WILLING TO HOLD OUT. FIRST BALLOT CONSTELLATIONS FROM WHICH HUNG JURIES ARE LIKELY TO RESULT SHOW A 6-6 VOTE IS 15 PERCENT LIKELY TO END IN A HUNG JURY, WHILE A 2-10 SPLIT WITH 10 UNDECIDED IS 7 PERCENT LIKELY TO END IN A HUNG JURY. A GROUP OF 4 OR 5 JURORS MUST CONSISTENTLY HOLD OUT FOR NO DECISION TO BE REACHED. A MATHEMATICAL MODEL TO TEST THESE FINDINGS IS DEVELOPED AND EXPLAINED. IT GIVES THE PROBABILITIES OF CONVICTIONS FOR JURIES OF VARIOUS SIZES AND CONFIGURATIONS. THEY ALL SHOW THAT ONE AND ONE-HALF TIMES AS MANY INNOCENT DEFENDANTS WILL BE CONVICTED AND TWICE AS MANY GUILTY DEFENDANTS ACQUITTED BY 6-MEMBER AS OPPOSED TO 12-MEMBER JURIES. REFERENCES ARE PROVIDED.