THE CONTROVERSY CONCERNS THE QUESTION OF WHETHER THE ADDITIONAL SEVERITY OF CAPITAL PUNISHMENT OVER LIFE IMPRISONMENT SERVES TO DETER POTENTIAL CRIMINALS. TO TEST THE DIFFERENTIAL DETERRENT EFFECTS OF SEVERITY AND CERTAINTY OF PUNISHMENT, RATES OF SKYJACKING ATTEMPTS WORLDWIDE ARE EXAMINED IN THE CONTEXT OF ATTEMPTS TO CURB THIS CRIME THROUGH MEASURES DESIGNED TO ENHANCE EITHER THE SEVERITY OR THE CERTAINTY OF PUNISHMENT. THE ANALYSIS INDICATES THAT INCREASING THE CERTAINTY OF PUNISHMENT RESULTS IN A DECREASE IN CRIME, WHILE INCREASING THE SEVERITY OF PUNISHMENT DOES NOT. THIS FINDING IS SAID TO ARGUE AGAINST THE NECESSITY OF THE DEATH PENALTY. SUPPORTING DATA AND A LIST OF REFERENCES ARE INCLUDED. (LKM)