A pure psychiatric harm is a special form of negligence which causes a person to suffer mental anguish, or has the potential to inflict such mental harm without causing any physical injury. Situations for pure psychiatric harm can also arise where claimants are never at the risk of sustaining a physical injury but are harmed psychiatrically because they have witnessed physical injury to other people Chadwick v British railways Board (1967). Examples of such situations can include people who happen to witness incidents of horrifying incidents.
As psychiatric harm is a form of negligence and therefore the same normal principles apply to establish a claim of it. Therefore, like in a general claim of negligence, the claimant in a claim of psychiatric harm would need to prove that the defendant owed a duty of care to him, that duty was breached, the breach caused damage, and that the damage was reasonably foreseeable.
Additionally, in a claim of psychiatric harm, two more conditions need to be satisfied: (a) the mental harm that the claimant suffered is a recognised medical condition which came on to the claimant as (b) a sudden shock rather then gradual damage. Failing to establish the four criteria under general principles of negligence, and the additional two rules for psychiatric harm would result in the claim not being accepted by the court.
Furthermore, a duty of care in psychiatric harm can also vary depending upon if the claimant is a primary or secondary victim. Claiming on the basis of a primary or secondary victim can consequently reduce or add extra requirements on top of the general duty discussed above. In essence, duty of care in psychiatric harm can greatly depend on how and at what level the claimant was involved in the situation e.g., whether he was directly or indirectly involved in the incident.