An econometric model is developed stipulating that time spent on illegal activity is a function of factors of unemployment, demographics, social conditions, risk of punishment, risk of imprisonment if caught and convicted, and the economic effects of both lawabiding and illegal activity. For the functional form of the model, time spent on illegal activities is converted to the number of illegal activities, a type of crime is specified, and time series data is used with the two-stage least squares method. Test results did indicate a negative correlation between crime and the two sentencing components. However, the apparent negative relationship could be a result of how sanction variables are measured and defined, a combination of a deterrent effect and other effects (like the fact that detained offenders cannot commit further crimes), or a third unidentifiable factor. In addition, it could be argued that the least squares method is inadequate for the research. When Ehrlich's model is looked at closely, several problems are apparent, particularly the fact that the negative correlation between number of crimes and the two punishment components cannot be positively designated a result of deterrence. Vandale, one of the main critics of Ehrlich's model, retested Ehrlich's data to introduce demographic and socioeconomic variables. However, his results did not show significant differences from Ehrlich's. Ehrlich's theoretical base and statistical methods appear to be fairly sound. Future research should take into account the effects of changes in the sentence for a certain offense and long-term effects of having served a sentence on the decision to offend again. Seventeen references and footnotes are included.