This area of tort has been the subject of uncertain development, therefore a claim specialist would need to help a claimant by assessing the case facts and applying them to the rules. From the start, it was decided that the claimant must be suffering a recognised psychiatric disorder for a claim to be available.

This meant there was no liability in Reilly v Merseyside Regional Health Authority (1994) as a couple who became trapped in a lift suffered insomnia and claustrophobia. This may seem unfair because claimants were clearly suffering, and the conditions may have had a large impact on their lives, yet they were not entitled to compensation.

As it is a narrow definition, it is also difficult to define and to prove, meaning it is led by the medical profession and is difficult to bring a claim, rendering it harsh on the claimant.

Claims for primary victims were originally based purely on the notion of foreseeability and of immediate fear for personal danger. For example, in Dulieu v White and Sons (1901) a woman was allowed to claim when a horse and cart crashed through the window of a pub where she was washing glasses and was therefore in fear of her own safety. This means it is not as restrictive for primary victims and is easier to claim, which is fairer for claimants.

The usual rules of negligence also apply to primary victims to make it easier to claim, including the thin skull rule. This means the defendant will be liable for the full extent of the damage to the claimant in the case of pre-existing conditions that have been worsened. In the case of Page v Smith (1996) the claimant was involved in a car accident caused by the negligence of the defendant. He suffered no physical injury but suffered a recurrence of chronic fatigue syndrome, which he had suffered some years earlier. This meant that the defendant was liable for psychological damage caused to the claimant.

Rescuers can also be classed as primary victims, for example in Chadwick v British Railways Board (1967) in which two trains crashed in a tunnel and a man who lived nearby was asked, because of his small size, to crawl into the wreckage and give injections to trapped passengers. He was able to claim successfully for the anxiety neurosis he suffered as a result. This was largely explained on the basis that he was a primary victim, himself at risk in the circumstances.

The law was later extended to include a claim for nervous shock as the result of witnessing a traumatic incident involving close family. People who were present at the scene and feared for the safety of a loved one were classified as secondary victims. For example, in the case of Hambrook v Stokes Bros (1925) a woman suffered nervous shock when she witnessed a runaway lorry going downhill towards where she had left her three children and then heard that the lorry had injured a child. It was held that it would be unfair not to compensate a mother who had feared for the safety of her children when she could have claimed if she only feared for her own safety.

This principle was even extended, at one point, to include shock suffered on witnessing events involving close but not related people, as in Dooley v Cammell Laird and Company (1951) in which a crane driver claimed successfully for nervous shock when he saw a load fall and thought that workmates underneath would have been injured. However, the courts did place a limit following this case, that claimants must be in the area of shock. This meant there was no liability in Bourhill v Young (1943) when a pregnant fishwife claimed to have suffered nervous shock after she heard a crash and then saw blood on the road, and then had a stillbirth. She was held to be outside the area of shock as it was unforeseeable because she was a stranger to the motorcyclist involved in the crash. This may also have been affected by policy reasons, as claimants must be compared to someone of reasonable phlegm and fortitude.

The current law on secondary victims is drawn from Alcock v Chief Constable of South Yorkshire (1992), in which it was decided that there must be sufficient proximity in time and space to the negligent incident, there must be a significant proximity of the relationship between the parties involved or the claimant must have been present at the scene as a rescuer, and the cause of the nervous shock must be the result of witnessing or hearing the traumatic event or immediate aftermath. This restricts the law to reduce claims, therefore a claim specialist will be suited to assessing whether or not a nervous shock claim is available.