Patent challenge is finally resolved after 28 years

In 1980 Fritz Amstrup filed a Danish patent application with a patent claim directed to a method of degreasing beef intestines by using a centrifuge. Amstrup fitted a timer to the centrifuge to allow control of the treatment time. According to Amstrup, keeping to a very precise treatment time provided a careful degreasing of the outside of the intestines, while preserving the internal mucous membrane. This was important for the saleability of the product in Japan where beef intestines are considered a delicacy. Amstrup’s patent attorney did not conduct a novelty search prior to the filing and the application contained no concrete substantiation of the alleged effect on the intestines. The Danish Patent and Trademark Office (DKPTO) novelty search revealed an earlier German patent for an identical centrifuge, which described the cleaning and removal of the mucous membrane, but did not mention a critical treatment time or automated time control.

According to current practice a patent cannot issue on the automation of a known process unless a particular effect is obtained that extends beyond the expected. Although it had not been shown or rendered probable that the treatment time was critical, the DKPTO accepted the application’s claims to that effect. Following protracted prosecution, including an extensive exchange of letters between Amstrup’s attorney and the DKPTO, the application was laid open in 1992 (in accordance with rules applicable at that time, according to which a patent did not issue until any oppositions had been decided on). At that point, DAT-Schaub AMBA filed an opposition on the grounds that the German patent described that inverted intestines could be treated to remove the mucous membrane and could be degreased by centrifuging, thus it was obvious to omit the inversion if the mucous side was to be spared. The initial opposition was rejected; however, the Danish Patents Board of Appeal reversed the decision on the grounds that the time control was obvious. In 1996 the opponent submitted to the appeal board a report describing a comprehensive test series supervised by an external expert which disproved the Amstrup allegation regarding the critical treatment time.

In 1997 Amstrup filed a new application restricted to the feature that the intestines were to be treated without being inverted. The application was subject to accelerated prosecution by the DKPTO and a patent issued later in 1997 (pursuant to the rules in force at the time, according to which patents issued prior to opposition). Again, DAT-Schaub lodged an opposition and referred to an earlier French patent describing treatment in a centrifuge of non-inverted or inverted intestines, depending on whether the intention was to remove the external fat, the internal mucus or both. The DKPTO maintained the patent in restricted form despite the opposition. DAT-Schaub appealed the decision, again leading to the appeal board revoking the patent due to a lack of inventive step.

Amstrup was granted legal aid to appeal the board’s decision before the Western Division of the High Court and DAT-Schaub entered the case as an intervening party in support of the appeal board. At the same time, Amstrup brought a case before the High Court claiming a large amount of damages from DAT-Schaub for alleged infringement of the patent. The appointed court expert asked to see the process in order to rule on the issue of the precise treatment time. As Amstrup did not have usable equipment at his disposal, DAT-Schaub made machinery available and tests were performed carrying out usual production with suitable time variations.

None of the tests performed supported the precise treatment time on which the DKPTO had relied in the previous two instances; thus, the tests provided in 1996 by the intervening party were confirmed. Based on this, in 2005 the Western Division of the High Court found for the Danish Patents Board of Appeal, ruling that the issuance of the patent was unjustified. This decision was upheld by the Danish Supreme Court on 21st August 2008. Therefore, the case regarding the alleged infringement also lapsed.

In this exceptional case the patent litigation took 28 years and was not concluded until eight years after any originally granted patent would have expired. Amstrup spent the first 12 years convincing the DKPTO of the patentability of his invention. Based on the opponent’s comprehensive tests in 1996, which raised some serious doubts as to the validity of the Amstrup claims, it would have been reasonable for the DKPTO to have demanded further substantiation from Amstrup before a patent issued and raised false expectations. Nonetheless – even after presentation of the pertinent French patent by DAT-Schaub – Amstrup used all the available appeal options, but at no time did he produce anything to justify a reversal of the board’s two negative decisions.

Ejvind Christiansen ([email protected])
Ellen Wetke ([email protected])


This is an insight article whose content has not been commissioned or written by the IAM editorial team, but which has been proofed and edited to run in accordance with the IAM style guide.

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