Criminal Law on the Principle of Men Rea: Self-Defense

Mental Errors that must be Proven

The rule of thumb guiding criminal law rests on the principle of men rea, which is ‘an act does not make an individual guilty unless the mind is guilty’. One is guilty of an act if there is evidence of evil mind, criminal purpose as well as having knowledge of the wrongful act. Mental fault classifications that must be proved include purposely, knowingly, recklessly and negligently (Gardner & Anderson, 2011) thus, an individual is guilty of an offense if he acted in one or more of afore mentioned states. In the case of Mr. X who was a construction worker, if he dropped the crossbar deliberately, this means that he acted on purpose and had the intent of committing evil.

For this reason, he is liable for first-degree murder. The same applies to scenario 2 where he threw the crossbar knowingly with the intention of seeing people scattering. In the third case where the worker threw the crowbar at another worker in a fight, but missed this is interpreted as having intent as well as will to harm his co-worker. The penalty he would face is similar to the previous scenarios. In the fort case where M. X came to work while drunk, his act will constitute negligence since his conduct as well as circumstance are known to him but his actions depicts a gross deviation from the standards of care that any reasonable person would uphold in his situation. He will then be charged of second-degree murder.

As suggested by Gardner & Anderson, 2011 the arguments available to X based on his degree of mental fault are based on ignorance or mistake. He should use this to negative purpose, knowledge, belief, recklessness and negligence. This will afford defense to Mr. X, however he might be found guilty of other offenses. In essence this argument will only help reduce the grade as well as degree of the offense which the offender might be convicted of if the situation had been contrary.

Use of Force in Self-defence

It is generally accepted for individuals to use force in self-defense when deemed necessary and the same must be proportional to the harm that one believes he may potentially be facing. Ideally, the force to be used should be non-deadly. First, it is important to establish a reasonable belief by using subjective as well as objective standards. The big challenge facing the court when trying to do justice to both sides seems eminent hence the jury needs to apply trier-of-fact. Additionally the threat to use force against an individual ought to be immediate. This means that one is not allowed to use self-defense for instance if warned by another person that if he repeats what he has done in the future, he will be punched or kicked. This is not sufficient to trigger the right to use self-defense (Eskridge, 2008).

According to Kopel, Gallant & Eisen, 2008 the law states that one must resort to self-defense when there is a strong reason and belief that it is necessary to prevent an attack. The same should be proportionate to the gravity of the attack. In this regard, it is not allowed if one is threatened to be slapped he or she should not respond by using a firearm. This will amount to excessive self-defense. Similarly the use of self-defense is not applicable in situations where the initial aggressor has withdrawn from the fight or confrontations and communicates the same to the victim.

However, if the victim continues with the confrontations and the aggressor is certain that the use of force might cause harm to him or her, he regains the right to use self-defense (Robinson, 2005). Similarly, in a third party scenario, one is not allowed to use self-defense to help another person unless he has reasonable belief that the victim deserves assistance. Some states require that when two individuals are engaged in a tussle, the one to rescue should be either a family member or a superior or an employee.


Eskridge, W. (2008). Dishonorable Passions: Sodomy Laws in America. New York: Penguin Group.

Gardner, T. & Anderson, T (2011). Criminal Law. London: Wadsworth.

Kopel, D., Gallant, P. & Eisen, J. (2008). The Human Right of Self-Defense. BYU Journal of Public Law, 22: 43–178.

Robinson, P. (2005). Criminal Law: Cases and Controversies. University of Pennsylvania: University of Pennsylvania Press.

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