Patent Litigation in Practice Series: Doctrine of Equivalents and Patent disclaimers in Hungary

The latest issue of our monthly series comes from Hungary where the courts have confirmed how the doctrine of equivalents (DoE) applies to patents containing disclaimers, creating a precedent that enhances predictability in infringement disputes. This decision underscores the importance of balancing broad protection with precise legal interpretation in patent claims. 

The patent and the allegedly infringing product 

In 2011 the patentee, a pharmaceutical manufacturer, filed an application for a preliminary injunction (PI) with the Metropolitan Court (Budapest) against a competitor. The basis of the PI application was a European patent designating Hungary. The main claim of the patent covered the combination of two known active ingredients with one or more excipient(s) commonly used in the pharmaceutical industry with the proviso, that the excipient was other than a calcium salt of phosphoric acid. The allegedly infringing product contained 2.5 w/w% of the excipient in a specific form, Dibasic Calcium Phosphate Anhydrous (DCPA). 

The patentee’s position 

The patentee claimed that the defendant’s product was infringing based on the DoE as it contained only a low amount of DCPA which could not have any technical effect. It argued that the defendant had included DCPA in its product only for the sole purpose of circumventing the patent. In addition, the main claim was a product claim and therefore the court should ignore the wording of dependent claims and the description of the patent when determining infringement. 

The defendant’s position

The defendant rejected the application of the DoE. It argued that the excipient was a disclaimer in the claim. The defendant relied on the teaching in the description according to which the technical problem was to find an alternative large scale manufacturing processes for the two well-known active ingredients without the use of calcium salt of phosphoric acid. It argued that the information disclosed in the description cannot be disregarded when applying the DoE to the patent in suit as the invention was basically finding the alternative manufacturing process without the said excipient. Therefore, the scope of protection cannot include products which contain the excipient subject to the disclaimer. 

The outcome of the proceedings  

The Metropolitan Court rejected the patentee’s application for a PI. The patentee did not appeal this order but commenced the main infringement action by filing a complaint against the defendant. In the main proceedings the court dismissed the complaint. 

The patentee appealed to the Metropolitan Appeal Court which upheld the judgment of the lower court. The patentee then filed a motion for permitting an extraordinary appeal with the Hungarian Supreme Court. However, the [high] court considered that the preconditions for admitting such a motion did not exist, namely that there was no need for harmonisation of case law as there are no diverging court decisions in relation to DoE. Another trigger for an extraordinary appeal is that the issue has significant social impact but in March 2024 the Supreme Court concluded that the DoE as such did not meet this criterion. 

Expert opinion in appeal phase 

The patentee requested the appeal court to appoint a judicial expert. The defendant tried to avoid this by requesting the court to appoint the Hungarian Intellectual Property Office to provide an interpretation of the description. The appeal court granted the patentee’s request and appointed a technical expert, but the expert did not then agree with the patentee’s arguments. The technical expert’s approach was that, for the DoE to apply, it was necessary to examine the technical problem and the solution, and consequently the technical teaching in the description and state-of-the-art cannot be ignored. 

Parallel Portuguese action

The patentee also sought to enforce the same patent based on DoE in Portugal. While the first instance decision was positive for the patentee, the appeal court rejected the complaint. It concluded that a patentee cannot have such a broad monopoly over equivalents which if it had included in the patent application, the patent would not have been granted. To this extent, the state-of-the-art is the limit to what the patent holder can claim when it comes to enforcement.

Practical impact 

This decision is relevant for businesses evaluating launch at risk strategy in Hungary. It adds certainty and predictability in cases where the patentee might rely on the DoE, confirming that the DoE cannot be used extensively. For patentees it demonstrates that Hungarian courts are prepared to assess an infringement claim based on the DoE and there is a good chance for success if the necessary preconditions are met and there is no risk that the claimed scope (based on the DoE) extends beyond the scope for which the patent was granted.