Are mentally unstable individuals liable for their crimes?

Their moral responsibility must be the measurement to rule their criminal responsibility. People with mental illness who committed crimes must be evaluated by experts (i.e. psychiatrists) to see how conscious they are in their actions. Treatment must come first before punishment. The imprisonment of such individuals diminish the reason on why are they being punish. Their lack of understanding on their crimes means lack of understanding on their punishment. “The simplest argument regarding the legal relation between civil wrongs and mental illness might run this way: in torts, liability is premised on fault; since the mentally ill are not in control of their acts they are not at fault and consequently, they should not be liable for their action.” (Alexander and Szasz, 1968)