The European Patent Office’s revocation of a key patent relating to the revolutionary CRISPR technology sent shockwaves around the IP world last week. While the much-discussed ongoing US CRISPR dispute has raised fundamental questions about obviousness, the European cancellation hinged on more technical factors concerning priority claims and international patent filing. As such, it has provided a stark reminder of the potential procedural pitfalls in patent procurement, especially with regard to use of the Patent Cooperation Treaty (PCT).

The decision – which upheld an earlier preliminary opinion – revoked a key CRISPR Cas-9-related patent owned by the Broad Institute, the Massachusetts-based research entity that pioneered the application of CRISPR Cas-9 for use in animal and plant cells.

Though this was the EPO’s first opposition ruling relating to the ground-breaking – and potentially highly-lucrative – genome editing technology, it is only the latest development in one of the many patent battles that have arisen around CRISPR in various parts of the world over recent years.

The original – and most-discussed – CRISPR dispute is taking place in the US, where the technology was first developed. There, the Broad Institute is in conflict with the University of California, Berkeley, which developed the foundational CRISPR Cas-9 methods, but only for use in bacterial cells. The west-coast entity is seeking to invalidate the Broad Institute’s US patent, whose claims, it argues, interfere with its own IP rights.

The Patent Trial and Appeal Board ruled in favour of the Massachusetts outfit last year, and Chief Judge Paul Michel (writing for IAM) has opined that the pending appeal from that decision “may be the case of the year in 2018”, because it “raises questions about the application of basic obviousness precedents and their attendant doctrinal standards and analytic methodologies”, which are crucial to almost all contentious and non-contentious patent matters.

But quite different factors were decisive in determining the fate of the Broad Institute’s patent in Europe: the EPO decision did not hinge on the nature of the technology and considerations of obviousness, but on procedural grounds relating to the validity of several priority rights on which the application’s claim to novelty rested.

In making its PCT filing in 2013 – from which its original EPO grant derived – the Broad Institute claimed priority from 12 of its earlier US applications from 2012. However, the EPO deemed that the institute had not properly obtained the right to claim priority from four of the original US filings. Contrary to European rules on priority rights, Luciano Marraffini of Rockefeller University – who was named in the earlier applications – was not cited as an inventor in the international registration. Only with those four priority claims invalidated, and additional prior art brought into consideration, was the patent found to lack novelty and revoked.

Last week’s decision, then, is a stark reminder that even highly valuable patents pertaining to revolutionary technological breakthroughs – including those at the centre of landmark disputes - may be lost as the result of what are possibly mundane procedural errors. Inventions protected via the PCT are often considered to be among the most valuable that an applicant may have as they are the ones deemed worthy of widespread international protection. Given that, it pays to ensure that every possible angle is explored before submission takes place. Broad has already stated that it will be appealing the EPO’s decision, but it may want to look a bit closer to home at what went wrong, too.