rationale behind his/her punishment is substantially impaired due to a medically recognized mental illness. 23. He also argued that in circumstances where a condemned prisoner develops a post-conviction mental illness and because of that mental illness, his/her mental faculties are not appreciative of the reason behind the punishment imposed by the Court, the execution of sentence would serve no purpose. He amplified that the retributive idea behind punishment is that it should not only serve as a deterrent, but also make one realize that he/she committed a wrong which has resulted in punishment. In the absence of such realization, due to an involuntarily induced mental disorder or illness, execution of a sentence loses its significance and may fail the test of proportionality attached to retributive justice. The learned amicus also argued that it is not every mental illness which would qualify for an exemption. The prohibition on executing mentally ill prisoners may be applied only to those who are medically found to be suffering from mental illness, the severity of which permanently impairs their ability to appreciate the rationale behind the punishment which they are sentenced to undergo. 24. The learned Additional Attorney General for Pakistan, learned Law Officers of all the Provinces as well as learned Advocate General, Islamabad adopted the submissions and contentions of learned amici Barrister Haider Rasul Mirza, ASC and Brigadier (Retd.) Professor Dr. Mowadat Hussain Rana. In particular, the learned Law Officers principally agreed with the contention of the amici curiae that death sentence should not be executed in case of those condemned prisoners who, due to mental illness, are unable to take rational decisions and understand the rationale behind their punishment. 25. We have heard all in detail, have considered their respective submissions and examined the relevant provisions of law with their able assistance. OPINION OF THE COURT 26. Before we embark upon to address the legal questions framed herein above, it is imperative to examine how the term "mental illness" has been defined in the domestic and foreign jurisdictions. 27. In our law, some terminologies/phrases/words such as "lunatic", "insane" and "unsound mind" have been used in the P.P.C., Cr.P.C and the Rules, regarding the mental health of an accused or a convict. But these terms have not been expressly defined in either of these Statutes/ Rules. 28. In Pakistan, the Mental Health Ordinance, 2001 (VIII of 2001) (Ordinance) was promulgated in the year 2001 which defined the terms "mental disorder", "mental impairment", "severe personality disorder", "severe mental impairment" and "mentally disordered prisoner". 29. However, after the passage of 18th Amendment, 'Health' became a Provincial subject and respective Governments of Sindh, Punjab, Khyber Pakhtunkhwa and Balochistan promulgated their own Acts in this behalf. These laws also define the terms "mental disorder" and "mentally disordered prisoners". The Ordinance was adopted by the Province of the Punjab and amended through the Punjab Mental