I have always been under the impression that in order to be entitled to an instruction on the issue of insanity, the Defendant would have to have on of their experts give an opinion that (1) the Defendant had a mental disease or defect and (2) that the defect prevented them from understanding the difference between right and wrong. However, I've not been able to locate the case on point.

It hasn't come to a head yet, but I get the impression that the defense attorney on one of my cases is going to ask the court to give them the instruction after only producing evidence of the mental disease or defect.

Dashield v. State, 110 S.W.3d 111, lays it out pretty thoroughly.

Thanks Jon. Very much appreciated.

Zack,
They can't just spring an insanity defense on you. They're required to give pretrial notice of an intent to raise it. See 46C.051

They filed their notice properly. Ultimately, no one was able to say the mental disease or defect caused the defendant not to know the difference between right and wrong.

The closest anyone got was saying the mental disease or defect combined with extreme intoxication caused the defendant not to know the difference between right and wrong.

We argued that this fell short of the defense's burden of production. Trial Court ultimately agreed.