mens rea

mens rea means intention to do or not to do something. e.g. when A poisons B with an intention to kill B, A has mens rea i.e. intention to kill B and A knows that he is poisoning B and as a result B will die.

e.g. 2 : A hits B by car due to rash driving and B dies. Here A had no intention to hit B and to kill him. this amounts to negligence on the part of A and there is no mens rea to kill B.

Hope this is useful.

Mens Rea refers to criminal intent. The literal translation from Latin is "guilty mind." The plural of mens rea is mentes rea. A mens rea​ refers to the state of mind statutorily required in order to convict a particular defendant of a particular crime.

The mens rea requirement is premised upon the idea that one must possess a guilty state of mind and be aware of his or her misconduct; however, a defendant need not know that their conduct is illegal to be guilty of a crime. Rather, the defendant must be conscious of the “facts that make his conduct fit the definition of the offense.”
Mental states are usually organized hierarchically by the offender’s state of blameworthiness. Generally, the blameworthiness of an actor’s mental state corresponds to the seriousness of the crime. Higher levels of blameworthiness typically correlate with more severe liability, and harsher sentencing.

For instance, let us take the case of the killing of Trayvon Martin. A jury believed George Zimmerman's story that he shot Trayvon Martin in self-defense. There was never any dispute that Zimmerman shot Martin. The dispute at trial turned on what was in Zimmerman's mind when he fired the gun.
Therefore, in order to convict Zimmerman, the prosecution had to prove that Zimmerman had criminal intent—mens rea. It failed to do that and Zimmerman was acquitted.

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Regards
Kevin M. Paul