AIPPI 2025 Study Question Q296: Preliminary Injunctions: Requirements for compensating damage suffered by defendant

One of the topics I discuss at some length in other forthcoming book, Wrongful Patent Assertion:  A Comparative Law and Economics Analysis (Oxford Univ. Press, forthcoming May 2026), is whether a patentee who obtains a preliminary injunction on the basis of a patent that subsequently is determined to be invalid or not infringed should be obligated to compensate the temporarily excluded defendant for its losses, and if so in what amount.  As I discuss in the book, practice around the world differs in many important respects.  Courts in the U.S. almost always limiting the patentee’s liability to the amount of the injunction bond it is required to post (which amount may turn out, ex post, to be undercompensatory).  The U.K. requires plaintiffs to agree to a cross-undertaking, essentially a contract obligating the payment of compensation in the event the preliminary injunction is thereafter lifted, while the CJEU has given mixed signals regarding what is permitted under EU law (see, e.g., discussion on this blog here).  Anyway, the AIPPI has made available its Resolution, its Summary Report, and the individual reports for 43 members, including not only the U.S. and the U.K. but also China, Japan, South Korea, India, several EU member states, and a smattering of countries in South America, Asia, and Middle East.  Among these members, there is substantial support for a rule that would require, as a general matter, full compensation of the defendant’s actual damages suffered as a result of the wrongly-issued preliminary injunction (as opposed to a more plaintiff-friendly approach that would limit liability to bad-faith assertions), albeit perhaps subject to some mitigating factors.  Whether or not you are an AIPPI member yourself, you can download all of the reports by going to aippi.org, clicking on “Library” and then “Search,” and then typing in “Q296.”

On this same topic, Hans-Jürgen Ahrens recently published an article titled Schadensersatz nach aufgehobener einstweiliger Verfügung wegen nichtigen Arzneimittelpatents—zugleich Besprechung von BGH GRUR 2025, 574—Glatirameracetat (Damages compensation following the lifting of a  preliminary injunction concerning an invalidated medicament patent—As well as case law of the Federal Supreme Court, GRUR 2025, 574—Glatirameracetate).  (The German case itself is related to the European Commission’s investigation of Teva relating to the drug Copaxone, which I have discussed previously here and will also be discussing, albeit briefly, in my forthcoming book.)  Here is a copy of the BGH decision itself, in which the court holds, inter alia, that the infringement defendant seeking to recover its own lost profit caused by the preliminary injunction may not also claim the infringer’s profit in excess of that lost profit—though it leaves open the question whether the defendant could choose to use any of the three methods for calculating its own actual loss, including the patentee’s profit, as the (single) method for estimating its actual loss.  For discussion of a recent British decision rejecting the argument that defendants may recover the plaintiff’s profits, see my previous blog post here.