Kitchin J. in his recent decision in M-Systems Flash Disk Pioneers Ltd v Trek 2000 International Ltd & Anor [2008] EWHC 102 (Pat) has found that a foreign judgment between the same parties, involving the same patent, will not operate as an issue estoppel between those parties in UK proceedings.

The original action was brought by M-Systems before the United Kingdom Comptroller, seeking revocation of Trek’s UK patent relating to data storage devices, including high capacity USB memory sticks. The parties had previously litigated the same patent before the courts in Singapore. In those proceedings, Trek had prevailed and the patent was held to be valid despite the invalidity objections raised by M-Systems.

M-Systems sought revocation of the patent in the United Kingdom based on various prior art disclosures, arguing that the patent lacked novelty and inventive step. In addition, it argued that Trek’s patent was insufficient and incorporated added subject-matter over the application as filed.

In response, Trek sought to amend its claims to incorporate further limitations relating to the smaller size and higher storage capacity of the claimed devices, as well as the fact these devices are connected directly to the computer’s USB port rather than through a USB cable. The Hearing Officer rejected the amendments on the ground that, if allowed, they would add subject matter over the application as filed. The Hearing Officer further held that, even if the amendments were accepted, he would not have exercised his discretion to amend the claims, as he was not provided with sufficient information as to when Trek had become aware of the prior art. Under the UK law relating to post-grant amendment that was applicable at the time of this decision, such conduct on the part of the patentee is a relevant factor in deciding whether discretion should be exercis ed in favour of the patentee.

Trek appealed against the Hearing Officer’s decision before Kitchin J. primarily on two grounds. Firstly, it argued that the judgment given by the Court of Appeal of Singapore should operate as an issue estoppel against M-Systems. Secondly, it argued that the Comptroller was wrong in holding that the amendments, if allowed, would add subject matter over and above the application as filed, as well as in refusing to exercise his dis cretion to allow the amendments.

The first point of Trek’s argument was rejected by Kitchin J. on both procedural and substantive grounds. Kitchin J. held that, since this issue was raised for the first time in the appeal, it should not be allowed to be argued by Trek. As regards the substantive issue, the Court held that there are considerable differences in the way the courts of Singapore apply Singaporean patent law, and the way UK courts apply UK patent law. For example, Singapore courts allow some matters, which are not admissible before the UK courts, to be taken into consideration in interpreting a patent. Hence, a judgment by the Court of Appeal of Singapore would not operate as an issue estoppel between the parties.

As regards the second point raised by Trek, the Court concurred with the Hearing Officer and held that the proposed amendments would result in added subject matter. Furthermore, on the question of exercise of discretion by the Hearing Officer, the Court held that the Hearing Officer had rightly declined to exercise his discretion to allow the amendments. The Court noted that the new Section 75(5) of the Patents Act 1977 introduced by the Patents Act 2004, would radically alter the approach that has been followed by the UK courts and the Comptroller in exercising discretion to allow proposed amendments. The new section 75(5) requires the Court and the Comptroller to have regard to the European Patent Office (EPO) practice in allowing the amendments proposed by the patentee. The current EPO practice does not take into account patentee’s conduct in allowing amendments to patents. However, Kitchin J. did not provide any guidance as to the extent to which the old UK practice of taking into account the patentee’s conduct and covetousness will be affected by the newly introduced amendment.