Ajinomoto Sweeteners Europe SAS v. ASDA Stores Ltd.,  EWCA Civ 609, presented an opportunity for the Court of Appeal to clarify some aspects of the law relating to the economic tort of malicious falsehood. In particular, the question was whether the ‘single meaning rule’ applied to malicious falsehood.
The single meaning rule developed in common law in relation to defamation cases. The classis statement of the rule is found in a passage in Slim v. Daily Telegraph,  2 QB 157, where Lord Justice Diplock expressed the rule in a clear statement:
“…Where, as in the present case, words are published to the millions of readers of a popular newspaper, the chances are that if the words are reasonably capable of being understood as bearing more than one meaning, some readers will have understood them as bearing one of those meanings and some will have understood them as bearing others of those meanings. But none of this matters. What does matter is what the adjudicator at the trial thinks is the one and only meaning that the readers as reasonable men should have collectively understood the words to bear. That is 'the natural and ordinary meaning' of words in an action for libel. Juries, in theory, must be unanimous upon every issue on which they have to adjudicate; and since the damages that they award must depend upon the defamatory meaning that they attribute to the words, they must all agree upon a single meaning as being the 'right' meaning. And so the unexpressed major premise, that any particular combination of words can bear but a single 'natural and ordinary meaning' which is 'right,' survived the transfer from judge to jury of the function of adjudicating upon the meaning of words in civil actions for libel…”
Essentially, the rule says that where two reasonable interpretations are possible, whether defamation has taken place or not must be ascertained by giving the words a single meaning. Thus, it is not sufficient to show that the words used by a defendant in a defamation case are possible to be interpreted in a defamatory manner. Instead, the words used must first be interpreted to mean one single thing (they must be given one single meaning) and then it must be seen whether that meaning is defamatory. In other words, it is not enough to show that a meaning of the words used is defamatory – it must be shown that the meaning of the words used is defamatory. The question before the Court of Appeal was whether this single meaning rule applied to cases of malicious falsehood also; and the judgment may have an important bearing in cases where a claim arises in tort on grounds of alleged commercial disparagement.
The plaintiff in the case was one of the world’s leading manufacturers and suppliers of aspartame (a sugar substitute). The defendant was a seller of health foods. One of its products carried a tag, “No hidden nasties... No artificial colours of flavours and no aspartame’. The plaintiff contended that this implied that the defendant was claiming ‘here is a risk that aspartame is harmful or unhealthy’. The defendant contended that the words simply meant that its product was intended for customers who found aspartame objectionable. The plaintiff argued that the single meaning rule did not apply to malicious falsehoods – it was enough if one of the reasonable meanings of the words used was objectionable. The defendant claimed that the single meaning rule was applicable; and that its preferred meaning was that single meaning.
The Court held in favour of the plaintiff, that the single meaning rule did not apply to malicious falsehood. Lord Justice Sedley concluded (Sir Scott Baker concurring), “On the judge's unchallenged findings, the meanings which reasonable consumers might put on Asda's health-food packaging include both the damaging and the innocuous. Why should the law not move on to proof of malice in relation to the damaging meaning and (if malice is proved) the consequential damage without artificially pruning the facts so as to presume the very thing – a single meaning - that the judge has found not to be the case? I do not accept that doing this will make trials of malicious falsehood claims unwieldy or over-complex. This is not because these claims are always tried by a judge alone: the experience of common law judges is that juries are on the whole very good at assimilating and applying sometimes complicated directions. It is because it makes the trial of the issues fairer and more realistic. Instead of (as here) denying any remedy to a claimant whose business has been injured in the eyes of some consumers on the illogical ground that it has not been injured in the eyes of others, or alternatively (and Mr Caldecott's case necessarily involves this) giving such a claimant a clear run to judgment when in the eyes of many customers the words have done it no harm, trial of plural meanings permits the damaging effect of the words to be put in perspective and both malice and (if it comes to it) damage to be more realistically gauged. For these reasons I would hold that the single meaning rule is not to be imported into the tort of malicious falsehood.” Additional reasons were provided by Lord Justice Rimer, “If the case were allowed to go to trial and the claimant were able to prove that such meaning was false, uttered with malice and calculated to damage it, why should it not be entitled to damages for the injury which the falsehood will have caused it? More importantly – and this is the primary remedy the claimant wants – why, if it can prove its case, should it not be entitled to have the defendant restrained by injunction from doing that which it wants to do, namely (presumably for its own commercial benefit) to continue to publish a falsehood that will continue to damage the claimant in the eyes of a substantial body of consumers? The result, however, of the application by the judge of the single meaning rule is that that body of consumers is removed from the court's radar. The court instead satisfies itself with the fiction, contrary to its own finding, that the entire consuming public will interpret the defendant's packaging as bearing a single innocuous meaning.”
Consequently, the single meaning rule has no application in the case of malicious falsehood. A reading of the judgment indicates that in cases of commercial disparagement, the single meaning rule from the law of defamation would have no application. Consequently, a cause of action would arise in a case of disparagement on showing that a reasonable meaning – as opposed to the meaning – of the defendant’s words is disparaging.