Rule 12.2 of The Federal Rules of Criminal Procedure provides that if a defendant intends to rely on an insanity defense or intends to offer expert testimony that he was suffering from a mental disease, defect or other mental condition which prevented him from forming a criminal intent, then he must notify the Government of this intention and file a copy of written notice to the Government with the Court. Here again, the basic purpose of the rule is to prevent surprise, eliminate unfair advantage and promote efficiency in the system. In the context of this kind of defense, were the rule otherwise, the Government could be surprised at trial having only been prepared to prove that the defendant committed the offense.
After receipt of a Rule 12.2 notice, the Government may file a motion with the Court to require the defendant to undergo a psychiatric examination performed by Government doctors. This, of course, will eliminate both the surprise and unfair advantage. Moreover, to ensure that there is no unfair advantage in this context, Congress has provided that evidence of a “mental defense” may be excluded if the required notices are not given or if the defendant refuses to undergo a psychiatric examination by Government psychiatrists.