Mens rea is principle of law associated with law of crimes. It says that, in order to constitute a crime mens rea is necessary. It must be accompanied with the actus reus (guilty act). However, it is not so in case of torts.
However, some qualification of the general statement is necessary. In torts, while ascertaining the liability of the wrongdoer, unlike in crimes of assault, false imprisonment, malicious prosecution, conspiracy or even battery, the state of the mind of the person committing the offence is irrelevant.
In the tort of negligence, certain amount of care is expected of a person and if he does not take the expected care, then he is liable for the tort. However, if he took expected care, then he will not be liable even if his act causes damage or injury to the other person.
Hence, if the conduct of a person is innocent in regard to the act done by him and injury is due to the inevitable accident, then he may not be liable for the tort. Thus, an injury caused to a drowning person in saving him and forcible feeding of a prisoner who is on hunger strike are not actionable acts.
Outstanding feature of law of tort is that the liability arises in some torts even when there is no bad intention, no malicious intention or motive to cause harm or injury. Therefore, if a statement made by a person turns out to be defamatory, he cannot take the plea that, he had no intention to defame.
This proposition can be illustrated with the help of the doctrine of strict liability in the light of the Ryland v. Fletcher case. It says, if a person makes a non-natural use of his land by collecting there something which is likely to do mischief on escaping, then he will be liable if the thing escape and causes damage. In such cases, he cannot take the defence that, he was not negligent in collecting it or allowing its escape.