THE CONSTANT PROMISE OFFERED BY THE STUDY OF THE NEUROLOGICAL ASPECTS OF DELINQUENCY IS RARELY FULFILLED. THE PROBLEM IS ESPECIALLY DIFFICULT SINCE NEARLY ALL EVIDENCE SUGGESTS THAT DELINQUENCY IS A RESPONSE TO A MIXTURE OF PHYSICAL, PSYCHOLOGICAL, AND SOCIAL HANDICAPS. BACKWARDNESS AT SCHOOL AND THE PRESSURES OF A LARGE FAMILY SEEM AS RELATED TO BEHAVIOR PROBLEMS AS EPILEPSY, ENCEPHALITIS, AND EVEN PRENATAL PROBLEMS. HOWEVER, WHILE A SMALL PROPORTION (5 TO 10 PERCENT) MAY BE CRIPPLED IN EARLY YEARS BY BIOPSYCHOSOCIAL PRESSURES, FOR THE REST OF THE HANDICAPPED CHILDREN--BOTH DELINQUENT AND NONDELINQUENT--THE MAIN EFFECT MAY BE TO MERELY DELAY RATHER THAN PREVENT THE ORDINARY SOCIAL LEARNING PROCESS. IN THE CASE OF ADULT OFFENDERS, WHERE THERE MAY BE A DEMONSTRABLE DETERIORATION FROM A NORMAL STANDARD OF PREVIOUS PERSONALITY AND SOCIAL ADJUSTMENT AS A RESULT OF DISEASE OR INJURY TO THE BRAIN, IT MIGHT BE EXPECTED THAT THESE EFFECTS ARE LESS COMMON, BUT MORE OBVIOUS AND DRAMATIC. THE MOST IMPORTANT POSSIBILITIES ARE THAT ABNORMALITIES OF THE BRAIN MAY PRODUCE SEX CRIMES, AGGRESSIVE CRIMES, AND FROM A MEDICOLEGAL VIEW, CRIMES ASSOCIATED WITH DISTURBANCES OF CONSCIOUSNESS. STUDIES IN ENGLAND, THE U.S., AND ELSEWHERE HAVE INDICATED A CONNECTION BETWEEN SUCH CONDITIONS AS TEMPORAL LOBE TUMORS AND EPILEPSY AND CONDITIONS OF HYPERSEXUALITY. OTHER STUDIES HAVE FOUND A HIGH PROPORTION OF ABNORMAL ELECTROENCEPHALOGRAMS AMONG MURDERERS. FURTHER, CASE ANALYSES HAVE FOUND THAT CONFIRMED BRAIN ABNORMALITIES MAY INTERRUPT CONSCIOUSNESS TO SUCH A DEGREE THAT AN OFFENDER MAY NOT BE RESPONSIBLE FOR HIS OR HER ACTIONS. IN LIGHT OF THE COMMON LAW DOCTRINE OF MENS REA (I.E., A GUILTY MIND), SUCH A MEDICOLEGAL CONSIDERATION MAY HAVE AN IMPACT ON THE RULING OF JUDGE AND JURY. REFERENCES ARE PROVIDED.