Dryden and Others v Johnson Matthey  UKSC 18 – read judgment
We are all made of stuff, and that stuff is not inert because it’s organic matter. Changes at the molecular level happen all the time, through cell death and replenishment, growth and the constant attrition caused by cosmic radiation on our DNA. Other changes are wrought by the environment or other organisms. Some changes are beneficial, even life saving, such as the removal of an appendix or the insertion of a pacemaker. The production of antibodies by vaccination have eradicated many diseases. Most of the time the body manages this itself. Every time certain cells in the blood encounter a foreign invader, they recruit the immune system to come up with a focussed weapon. This is an antibody, which lies dormant until the threat (the antigen) arises again. Antibodies are good things to have around until they’re provoked by enemies akin to the ones that created them, whereupon the body produces an allergic reaction to get rid of the toxin/allergen.
So, does the triggering of an antibody (an immunoglobulin molecule) constitute tortious injury, sounding in damages? This is the question raised by this case, and it goes to the heart of what “injury” is for the purposes of the law.
The three appellants had been employed in factories making catalytic converters. As a result of some slipshod management they had been exposed to platinum salts and had consequently become sensitised to them. People sensitised to platinum salts produce a particular type of antibody in their immune systems, which is only activated when exposed to more of these salts. The employees’ sensitisation was detected through routine workplace testing and as a result they were no longer permitted to work in areas where they might be exposed to platinum salts. One employee was redeployed within the company, the other two were dismissed under special termination conditions.
All three asserted that they had suffered a loss of earnings or earning capacity by reason of the fact that they were no longer able to work in any environment where further exposure to platinum salts might occur.
So far, so straightforward. But even admitted negligence and breach of statutory duty are not actionable per se, without injury. On the face of it, the employees had suffered pure economic loss, and this is not recoverable in tort. That is at least what the trial judge concluded, and his view was endorsed by the Court of Appeal ( EWCA Civ 408;  1 WLR 4487). Lord Justice Sales, with whom the other members of the court agreed, endorsed Jay J’s view that the claimants had suffered no actionable personal injury. He saw the physiological change of platinum salt sensitisation as
not harmful in itself in any relevant sense
and concluded that it was not converted into actionable injury by the resulting removal of the claimants from their jobs, with detrimental financial consequences.
Arguments before the Court
The issue before the Supreme Court was therefore whether platinum salt sensitisation qualified as an actionable personal injury. Lady Black, giving judgment, summarised the nature of the harm thus:
A person who has been sensitised but has not yet developed symptoms is not limited in any way in their life, except that they must avoid circumstances in which they are exposed to platinum salts. Platinum salts are not encountered in everyday life, only in certain specialised workplaces. (para 7)
“Physical” or “personal” injury is loosely defined in common law, although it features as a concept in various legislative provisions, again without definition. For example in the 1980 Limitation Act it is expressly said to include “any disease and any impairment of a person’s physical or mental condition” (Section 38). But how far does this definition go? Many forms of life threatening pathologies, such as cancer, are asymptomatic for months or years before they are diagnosed. Modern medicine has developed ways of detecting these silent enemies. But if the injury is painless and inert until some novus causus interviens triggers it, should it sound in damages?
To be actionable in tort, damage has to be more than negligible. Change itself cannot be actionable as personal injury; if the damage causes no pain or symptoms, it might be a matter of de minimis non curat lex. In one of the leading asbestosis cases – where claimants were left with plaques on their lung tissue after workplace exposure – the House of Lords concluded that even pleural plaques, without more, could not ground a claim in tort. Damage has to be proved, as Lord Hoffman said:
Damage in this sense is an abstract concept of being worse off, physically or economically, so that compensation is an appropriate remedy. It does not mean simply a physical change, which is consistent with making one better, as in the case of a successful operation, or with being neutral, having no perceptible effect upon one’s health or capability. (Rothwell v Chemical & Insulating Co Ltd  AC 281 ).
The respondent company contended that the effect of the platinum salts on the claimants’ bodies did not amount to physical damage to bodily tissue or an impediment to the proper working of bodily tissues or organs. The molecular change that had occurred was in their submission entirely normal and benign in character, as a person will naturally develop antibodies in everyday life and antibodies are not themselves harmful. Indeed, in the defendant company’s view,
But even if sensitisation (generation of antibodies) were to be taken as a form of physical injury, said the defendant company, it should only be actionable if triggered by something in everyday life, such as sunlight. In such a case the claimants would have sustained actionable damage because they would not be able to carry on with their ordinary life and would suffer, as the defendants put it, a “deficit” which would undoubtedly be characterised as personal injury.
The Supreme Court rejected these arguments and allowed the employees’ appeal.
Reasoning behind the decision
Although the concept of personal injury is somewhat inchoate, it could include this form of sensitisation. As Lady Black said, it was not “inappropriate” to view the development of a platinum salts allergy in a person who does not, at the outset, have a sensitivity to platinum salts as having two stages:
first comes sensitisation, next comes allergy.
Platinum salt sensitisation could therefore not be classed merely as the development of a benign antibody. The antibody produced was likely to react to further exposure to platinum salts so as to produce allergic symptoms, and it was common ground that a platinum salts allergy itself amounted to an actionable personal injury.
Given that the employees would be likely to experience symptoms upon further exposure to platinum salts, their bodily capacity for work had been impaired and they were therefore significantly worse off. The situation in this case had to be distinguished from Rothwell v Chemical & Insulating Co Ltd  AC 281 . That case concerned the development of pleural plaques as a result of exposure to asbestos fibres. Pleural plaques were nothing more than a marker of exposure to asbestos dust; they were symptomless in themselves and neither led nor contributed to any condition that would produce symptoms, even if the sufferer were to be exposed to further asbestos dust. Sensitisation to platinum salts constituted a change in the individual’s physiological make-up which meant that further exposure carried the risk of an allergic reaction and meant that sensitised individuals had to make changes to their everyday lives to avoid further exposure.
As I observed at the top of this post, this case probes the meaning of “personal” or “physical” injury in law. And its implications go further than injury to the body. What about the incursion of roots of a certain invasive plant over property boundaries? If these roots do not actually impair the fabric of the second property, in what way can they be said to “damage” it so as to give rise to compensation? And how can liability in tort keep pace with advancing technologies that can detect microscopic changes, in our bodies, in the air, land, or in the water? The task of the courts, to find the bright line between physical injury or damage, and “pure” economic loss, becomes ever more challenging.