"Under Police Commissioner Draco, the city of Spartanburg began jailing people for committing petty crimes such as littering, shoplifting, and spraying graffiti. Criminals in Spartanburg must have understood that lawlessness would no longer be tolerated, because the following year Spartanburg saw a 20% drop in violent crimes such as homicide. Our town should learn from Commissioner Draco's success, and begin a large-scale crackdown on petty crime."

The argument concerns the policies of Draco, the new town commissioner.Draco employed new policies of jailing people for committing petty crimes such as littering, shoplifting etc.These policies have been attributed to have caused a deterrent effect on Spartunburg's violent crime rate.A neighboring town plans to employ a similar policy of jailing people for committing petty crimes such as littering, shoplifting etc.. The argument first assumes that the strictness on petty crime will deter people to commit violent crimes ,and second assumes that the new policy will have similar effects on the neighboring town.
Firstly, The argument suggests that the policy of jailing people for petty crimes has had a deterrent effect on the people of Spartanburg ,but doesn't provide any causal relation between the two types of crime. If only the new policy of jailing people for petty crimes has been implemented and punishments for people, who have committed violent crimes remains unchanged then the new policies will not instill fear in the people, who commit violent crimes.
Secondly,The argument doesn't consider the alternate explanations for the decrease in crime in Spartanburg. A more likely explanation for the decrease in crime could be the number of people jailed in the previous year before the new policy was put in action. This number could be abnormally high and thus the total number of people ,who could have committed the crimes, could be reduced. The lower crime rate could be attributed to lower number of violent people rather than the new policy.
Thirdly,A policy that could have worked in one town will not necessarily work in another town.The argument must consider the reaction of people in the neighboring town.It could be a very bad idea to implement this new policy if a high percentage of people in neighboring town empathize with people,who are shoplifters or regularly commit petty crimes, and such a policy could result in a lot of people causing protests or even riots. If this fact is true the argument is significantly weakened.
The argument is weak and incoherent.It doesn't provide enough evidence as to why such a policy will have the intended effect.Since the argument doesn't explain how this new policy changed the crime rate, consider other different possibilities ,and effect of the policy on the neighboring town.This argument is flawed and can be improved .