Liability or responsibility is the word or tie that comes into existence as a result of the wrongful act of an individual. This is called Vinculum juris by which a man who is under it, must do certain things. A man's liability consists in these things which he must suffer. It is the ultimatum of the law. It has its sources in the Supreme will of the State. According to Salmond, liability or responsibility is the bond of necessity that exists between the wrong doer, and the remedy. "He who commits a wrong is said to be liable or responsible for it". Liability may be divided either as civil or criminal or as remedial or penal. In the case of civil or remedial liability, the object of the law is the enforcement of right, whereas in case of criminal or penal liability the purpose is the punishment of the wrong-doer. All criminal liability is penal. Civil liability on the other hand may be either penal or remedial.
Measure of Penal liability : Mens rea:
The basic principle of a liability is embodied in the legal maxim. "Actus non facit reum nisi mens sit rea". [The act alone does not amount to guilt, it must be accompanied by a guilty mind, "mens rea"]. Hence, there are two conditions to be fulfilled before penal liability can be imposed on a person. It is not enough that a man has done some act. Before the law can justify punishment, an enquiry must be made into the mental attitude of the doer. It is the combination of physical and mental elements that constitutes penal liability. It is not enough to •convict an accused charged of the offence of murder to prove that he has killed another. It should further be proved that he did it intentionally, wilfully and deliberately. According to Salmond, generally a man is penalty responsible for those wrongful acts which he does either wilfully or negligently.
There are three aspects of penal liability viz., conditions, incidence and measure of penal liability. According to Salmond these threeelements should be taken into consideration in determining the measure of criminal liability, namely, motive of the offender, the magnitude of the offence, character of the offender. Where there is no inadvertence or negligence, punishment is generally unjustifiable. Hence in inevitable accidents or mistake it is in general a sufficient ground of exemption from penal responsibility.
Ex. A driver knowing fully well, that the bus is not having the breaks, insists to drive the bus; In consequence the bus has gone out of control and has resulted in an accident injuring B. This is an act committed intentionally and hence the driver is liablefor punishment. Here the "Mens Rea" (blame worthy mind) is there. But if the bus has been in good condition as regards breaks system, then while driving, if the accident happens, it could have been said that the accident is inevitable. It has taken place accidentally. Here the driver has no idea of accident but it is due to failure of the breaks the accident has inevitably occurred. Father was sleeping in a room which was dark and there was a gun kept loaded in that room. His son entered the room, in darkness; the son pressed the trigger of the gun thinking it to be a switch which resulted in firing of the gun resulting in the death of the father. Father was the victimof the bullet but the son had no intention to kill his father. This is inevitable accident not murder.