A recent ruling in the Chancery Division is likely to cause concern to those who are on the receiving end of comparative or "knocking" advertising copy.
The judge applied principles that are normally associated with defamation to his decision on whether or not to grant interlocutory relief in a pending trademark infringement and malicious falsehood action.
The dispute involves two of the country's leading nursing publications, The Nursing Times and The Nursing Standard. It relates to an advertisement run by the Nursing Standard, in which comparisons were made with its rival The Nursing Times, which is a registered trademark owned by Macmillan.
The use of someone else's registered trademark in this manner can amount to an infringement without the defence provided by s10 of the Trade Marks Act 1994. This section permits use of another's registered trademark for comparative advertising purposes, but stipulates that such use must be "in accordance with honest practices in industrial or commercial matters".
Macmillan claims that some statements in the advertisement did not fall within this proviso and that, in any case, the advertisement amounted to malicious falsehood.
The publishing house sought an interlocutory injunction to restrain further publication of the advertisement pending trial. However, Mr Justice Neuberger refused to grant early injunctive relief. In doing so he followed the long-established principle under which interlocutory injunctions are refused in defamation actions in the interest of maintaining free speech, where the defendants say they intend to justify what they have said.
The judge's rationale was based on the American Cyanamid principles, which relate to the factors to be taken into account by a court in deciding whether or not an injunction should be granted. Where these factors are evenly balanced and the defendant claims that what it had done can be justified, the judge took the view that to award an interim injunction would be wrong.
Timothy Bamford, partner in the intellectual property department at Charles Russell, which represents the Royal College of Nursing, acted for The Nursing Standard in the claim against it by The Nursing Times.
"This decision could herald a new and possibly decisive factor in claims for interlocutory injunctions in the context of comparative advertising," he said. "The established American Cyanamid principles are well-known. Where the so-called 'balance of convenience' is evenly poised between the parties, the principle of freedom of speech could be decisive."
Mr Justice Neuberger said that each party had an arguable case and that the balance of prejudice was "pretty even". He said that it was hard to say whether or not granting an injunction would cause more damage.
"In a sense, therefore, I fall back on what is the principle of free speech," he said.
Caroline Temperton, senior assistant at Charles Russell, who prepared the The Nursing Standard's defence, said : "A further point of guidance was the judge's suggestion that comparative advertisements aimed at a specialist audience should be judged by the effect they would have on that audience - in this case advertisers - and not by the effect they would have on the public at large."