Jeffrey dahmer was judged to be legally sane at the time he killed and dismembered 15 individuals. this indicates that the jury believed that dahmer:

   Was able to appreciate the wrongfulness of his behaviour and control it

Explanation:  It simply means, and what is regulated by law, that anyone who is perfectly healthy, that is, of a sound mind when committing a crime, means that they are aware of what they have committed and can bear full responsibility for the crime committed. It is part of the law regarding mental health, and Jeffrey was in his sanity when committing the crime, so he could fully understand and realise his actions, that is, appreciate the wrongness of what he was doing. The legal expression for this term is compos mentis. Based on the assessment that Jeffrey was of sound mind at the time of his crime, the jury decides that he must bear full responsibility for the said actions.

good question. i'll be looking into that. (this is a joke sir)