What is the difference between mental illness and insanity?

In your reading, A Matter Over Mind, the author presents the case of a young man who shoots and kills a police officer. The case argues a defendant’s constitutional right to use the insanity defense and the amount of leeway provided to prosecutors.

What is the difference between mental illness and insanity? (Hint: What is the important second prong of the McNaughten rule?)
The McNaughten rule cannot be used to defend the actions of a person who drinks alcohol and then murders someone. Why not?
Identify each of the following:
Rational and guilty
Guilty but insane
Not guilty by reason of insanity
If you were deciding this case, how would you rule? Briefly explain your decision.