Tehrani v Bonaduz AG & Ors.

A post-trial patent amendment which introduces a substantially new claim, likely to require a further validity trial, will generally be refused where the relevant point could have been raised before the original trial. The rule in Henderson v Henderson and the overriding objective apply to the timing and conduct of patent amendment applications. A party cannot justify delay by saying that the significance of the disputed wording was not anticipated where the issue was clearly identified in the evidence and at trial. Individual litigants may receive additional latitude, but that factor carries little weight where the party had professional advice and representation.

The claimant, a patentee, applied under section 75 of the Patents Act 1977 to amend claims concerning automatic control of positive end expiratory pressure and oxygen concentration for the next breath of a patient.

The patent had previously been found invalid, principally because claim 1 lacked novelty over prior art known as Waisel. The proposed amendments changed indefinite articles to definite articles and would potentially generate a new validity challenge requiring a further trial. The issue was whether the amendments should be permitted after trial.

1. Application dismissed. The proposed amendments were amendments of the type identified in Nikken Kosakusho Works v Pioneer Trading Co: they were designed to establish a new claim which had not been adjudicated at trial.
2. As explained in Warner-Lambert Company LLC v Generics (UK) Ltd and another, where such an amendment would provoke a validity challenge requiring a further trial, the rule in Henderson v Henderson and the CPR overriding objective will generally militate against permission if the amendment could have been made in time for the first trial. The Supreme Court’s reasoning was at least of the highest persuasive authority and was followed.
3. The distinction between “a next breath” and “the next breath” had been clearly raised in the defendant’s expert evidence, addressed in the claimant’s response, argued at trial and discussed in the earlier judgment. The claimant could therefore have made a conditional amendment application before or during trial. Her asserted inability to anticipate the significance of the issue did not justify the delay.
4. The fact that the claimant was an individual litigant did not alter the result. Although additional latitude may sometimes be appropriate, she had been professionally advised before and during the trial.
5. The reference in article 138(3) of the EPC 2000 to amendment rights did not displace national procedural rules governing the timing, grant or refusal of amendments, nor did it legitimise an otherwise abusive use of the court’s process.

The application to amend the patent was dismissed.

The judgment records that judgment had previously been handed down on 22 December 2021, declaring the patent invalid principally for lack of novelty over Waisel. The present decision concerned the claimant’s subsequent application to amend the patent.