Irish role in European patent litigation strategy highlighted

Dublin-based Karen Gallagher of Pinsent Masons was commenting after generic medicines manufacturer Sandoz successfully challenged the validity of a patent owned by rival pharmaceutical company Bayer – and, in the process, brought information that might potentially aid its case in parallel proceedings in other jurisdictions into the public domain.

The patent in question was the Irish part of a European patent that covers the dosage regimen for the drug rivaroxaban. Rivaroxaban is used to prevent or treat blood clots. Bayer’s patent for rivaroxaban, which it markets under the brand name Xarelto, expired in 2024, but the patent for the dosage regimen was not due to expire until 19 January 2026. Sandoz has launched a rival generic version to compete with Xarelto in Ireland and, along with other generic medicine manufacturers, has challenged the validity of the European patent in other jurisdictions.

The judgment of the High Court in Ireland finding the patent invalid was handed down in June, but it was only recently published. This is because Bayer had applied to keep confidential information disclosed in the course of the trial from entering the public domain.

The documents in question were documents that Bayer had disclosed to Sandoz’s lawyers as part of the discovery process – an essential process in litigation that provides for the exchange of documents between the parties to allow them to better understand one another’s case. The documents Bayer disclosed were subject to a confidentiality agreement, which imposed significant restrictions on how Sandoz could use them.

However, because the documents were the subject of detailed evidence and argument at a trial heard in public – some of them having been deployed in the proceedings as attachments to supplemental expert reports and referred to in oral evidence – the information that came to light from that process did not benefit from the confidentiality agreement.

In a sworn statement given to the court, a European patent attorney at Bayer said the information held both clinical and commercial value and described how another company could use it to obtain a competitive advantage. The company applied to the court for an injunction to apply “protective measures” in relation to that information. Lawyers for Sandoz challenged the need for a confidentiality order to be applied, arguing that lots of information about rivaroxaban’s development that Bayer sought to keep private was already in the public domain.

The judge, Mr Justice Rory Mulcahy, initially granted an interim confidentiality order – which is why the June ruling was not published at the time – but he has now rejected Bayer’s application for the protective measures to apply permanently. The June ruling has now been published, with some redactions, along with a second judgment regarding the confidentiality order application; and previously confidential information surfaced during the trial is now considered in the public domain.

“The decisions are significant as they highlight the strategic importance of expert cross examination and discovery in Irish proceedings in broader European patent litigation strategy,” said Gallagher.

“Specifically, the judgment on the confidentiality application confirms that once discovery documents – even those marked confidential – are opened in court, including by inclusion in expert reports, they lose their confidential nature. This means the receiving party may be released from the implied undertaking to only use those documents for the purposes of the proceedings, and may refer to them in parallel proceedings in other jurisdictions. Often, court permission is sought for the use of discovery documents in this way, if the disclosing party objects,” she said.

“Expert witnesses are often subject to rigorous cross examination in Irish proceedings, and documents obtained on discovery may be put to the witnesses in cross examination. The substantive judgment contained some criticism of Bayer’s experts, including shifts in their evidence between their witness statements and in cross examination. Inferences were also drawn from the experts' failure to reassess their position on certain points in light of information disclosed in discovery documents,” she added.

Extracts from cross examination and from discovery documents are quoted in the judgment, meaning that third parties who are challenging the patent in other jurisdictions may refer to these extracts in their own proceedings, according to Gallagher.

“Another point worth noting is that these proceedings went to trial under one year from the date of issue, and judgment was handed down four weeks after the trial concluded,” she said. “The speed with which the case progressed demonstrates that Irish judges are now keenly aware of the need for urgency in patent revocation proceedings.”