Nikken Kosakusho Works & Anor v Pioneer Trading Company & Anor

A court will ordinarily refuse a post-trial validating amendment to a patent where it would introduce a new validity issue and require a further trial. Patent litigants, like other litigants, must bring forward their whole case in time for it to be resolved at the existing trial. The Henderson v Henderson principle and the overriding objective in the CPR favour early identification of issues, economy, fairness and finality. The potential value of the patent, and an offer to pay costs, do not justify a second validity trial or continued commercial uncertainty.

The appellants' United Kingdom patent for a high-speed tool chuck was held invalid by Mann J in an unappealed first judgment, 2004 EWHC 2246 Ch. The patentees then sought permission under section 75 of the Patents Act 1977 to replace the expression “predetermined depth” with “approximately 3 to 5mm in depth”.

In a second judgment, Mann J refused permission both as a matter of discretion and on an added-matter ground under section 76(3): 2004 EWHC 2426 Pat. The patentees appealed the discretionary refusal. The central issue was whether a validating amendment should be permitted after trial when it could generate a fresh contest about the validity of the amended claim.

1. Appeal dismissed. The court unanimously upheld Mann J’s discretionary refusal to permit the proposed amendment. Jacob LJ gave the principal judgment; Laws LJ and Waller LJ agreed.

2. The proposed amendment would advance a claim that had not been in issue at trial. The respondent would be entitled to contend that implementation of the prior art with a groove of the proposed depth was obvious. That issue had not been investigated by evidence, and its resolution would require a second validity trial.

3. The discretion under section 75 of the Patents Act 1977 had to be exercised consistently with the principle in Henderson v Henderson: parties must bring their whole case forward. That principle applies as fully to patent litigation as to other litigation. The patent authorities, including Windsurfing v Tabur Marine [1985] RPC 59 and Lubrizol Corp v Esso Petroleum Co Ltd [1998] RPC 727, confirmed that a successful defendant should not ordinarily be subjected to a fresh trial on a new basis for a monopoly claim.

4. The CPR reinforced that conclusion. A further trial would increase expense, delay final resolution and conflict with active case management. Costs could not cure the unfairness or the commercial uncertainty caused by prolonging a patent-validity dispute. A patentee facing a real construction issue should consider and seek any necessary amendment sufficiently early for it to be addressed at trial.

5. There was no special rule for patents. The court therefore did not need to decide whether the amendment would contravene section 76(3), and Jacob LJ did not endorse Mann J’s approach to that issue. The appeal was dismissed with costs, including the costs of the respondents’ notice.

• Court of Appeal (Civil Division) Dismissed the patentees’ appeal and upheld the refusal of permission to make a post-trial validating amendment.

• High Court, Chancery Division (Patent Office) Mann J held the patent invalid in an unappealed judgment, 2004 EWHC 2246 Ch. He subsequently refused permission to amend the patent in 2004 EWHC 2426 Pat, which was the judgment under appeal.