This could lead to much unhappiness to the community to which Dan lives because of all the problems drug abuse has. The benefits of keeping the marijuana in as evidence is that the prosecutor of the case will win, drugs are off the streets, and the person who was in possession of an illegal drug will be convicted. Throwing out the marijuana as evidence would bring happiness to the defendant's attorney. It would also bring happiness to the defendant's family, friends, and co-workers. The benefits of throwing out the evidence would be that the 4 th Amendment would not be violated, and Dan would not lose his freedom.
Utilitarians use general rules of thumb.
However, there are exceptions. Relationships get damaged by drug abuse. The consequences of getting caught by the law bring much unhappiness because the person could be put in jail or have to pay a high fine. An exception to this rule of thumb would be, for example, medical use of marijuana. In this case, marijuana would have the consequences of helping someone live a better life than they would if they were not allowed access to it.