Lord Justice Jacob made his comments in a Court of Appeal ruling in a dispute between the European Central Bank and Document Security Systems (DSS), a US company that has accused the Bank of infringing its technology in the production of euro banknotes.

The Court yesterday backed the UK High Court, which ruled in March 2007 that DSS's European patent EP UK 0 455 750 was invalid. Since then, the patent has been upheld in first instance courts in the Netherlands and Germany but invalidated in France.

Jacob described the different rulings as "deeply regrettable".

"It illustrates yet again the need for a one-stop patent shop (with a ground floor department for first instance and a first floor department for second instance) for those who have Europe-wide businesses".

Jacob is a long-time supporter of the European Patent Litigation Agreement (EPLA), a plan to set up a Europe-wide system of patent litigation. He chaired a committee of judges that drew up draft procedural guidelines for the proposed EPLA court and has said in the past that the EPLA is the only solution to the problem of Europe's fragmented system of patent litigation.

However, the EPLA has met with considerable resistance from a number of EU member states, led by France, and is unlikely to be introduced.

The dispute between DSS and the European Central Bank began three years ago when the US company sued the bank in August 2005 at the European Court of First Instance, alleging that the euro banknotes produced by the ECB infringe its European patent relating to anti-counterfeiting technology.

But it suffered a setback last September when the CFI declined to accept jurisdiction in the patent case. The Bank subsequently filed a series of lawsuits in national courts seeking to cancel DSS's patent.

In his judgment yesterday, which was supported by Lord Justice Lloyd and Sir John Chadwick, Jacob highlighted comments made by Mr Justice Kitchin, the High Court judge who heard the case at first instance, in which he said that the positions adopted by DSS in the UK court and the CFI were "radically different".

Kitchin had gone on to say that the case illustrates why it is desirable to try infringement and validity issues together, where at all possible: "If they are tried separately it is all too easy for the patentee to argue for a narrow interpretation of his claim when defending it but an expansive interpretation when asserting infringement."

Jacob added his own interpretation of the problem: "Professor Mario Franzosi likens a patentee to an Angora cat. When validity is challenged, the patentee says his patent is very small: the cat with its fur smoothed down, cuddly and sleepy. But when the patentee goes on the attack, the fur bristles, the cat is twice the size with teeth bared and eyes ablaze."