Reviewing Dijkman’s Proportionality Test: Rethinking the Boundaries of Patent Injunctions

Today, I would like to offer a review of Léon Dijkman’s The Proportionality Test in European Patent Law and the UPC, a timely and ambitious contribution to the fast-evolving law of patent remedies in Europe. I am grateful to the author for sharing a copy of the book.

The very first encounter with it is visual rather than conceptual: the cover reproduces Henri Rousseau’s Combat du tigre et du buffle, an improbable struggle suspended in lush, stylized vegetation. One wonders what resonance Dijkman sought in this choice — the asymmetry of forces, the ambiguity of aggression, or perhaps the reminder that legal conflicts, like wild ones, rarely conform to doctrinal geometry. Whatever the intention, it is a striking image, and a beautiful one, gently preparing the reader for a work that grapples with imbalance, power, and restraint.

Introducing the Book: Origin, Structure, and Purpose

Dijkman’s The Proportionality Test in European Patent Law and the UPC is a substantial monograph of roughly 264 pages, published by Hart and derived from the author’s doctoral dissertation at the European University Institute. It bears all the hallmarks of a first-rate PhD — conceptual ambition, doctrinal precision, and a willingness to interrogate foundational assumptions — while also reflecting the refinement of post-doctoral research and further engagement with the emerging UPC landscape.

The book is structured in three parts.
The first lays out the conceptual and historical underpinnings of proportionality in private law and EU law, situating the principle within fundamental rights doctrine and longstanding debates on the automaticity of injunctions. The second part diagnoses the structural imbalances of contemporary patent litigation, including the rise of component patents, risks of hold-up, and an impressively detailed analysis of post-eBay American case law. The third part sets out Dijkman’s own proportionality framework — articulated through the categories of overreach, abuse, and third-party rights — each developed with doctrinal clarity and comparative insight.

The architecture is clean and deliberate: theory, diagnosis, prescription. It positions the book not merely as a contribution to the literature, but as one of the most ambitious attempts in recent years to articulate a coherent, operational understanding of proportionality in European patent law at the precise moment when the UPC is beginning to crystallize its remedial jurisprudence.

A Bold Attempt to Reframe a Familiar Debate

Some books clarify; others reorganize; a rare few attempt to redraw the contours of a legal idea we believed settled. Dijkman’s book belongs to this last category. It enters directly into a longstanding tension in patent law: whether an injunction naturally follows from infringement, or whether its scope must always be disciplined by judicial scrutiny.

Rejecting sprawling, policy-heavy balancing tests, the author proposes a doctrinal recalibration. Proportionality, he argues, should anchor itself in a principle internal to patent law: commensurate scope. An injunction is proportionate when its real-world force does not exceed the technical contribution of the invention. When suppressing infringement effectively immobilizes an entire product because of a minor patented component, the legitimacy of the remedy becomes contestable.

It is an elegant reframing; one that speaks the language of courts and gives the debate a clarity that has often been lacking. Yet this very elegance opens the door to deeper questions.

The Shadow of Josserand: Abuse of Rights as a Forgotten Lens

Dijkman structures proportionality around three categories: overreach, abuse, and third-party rights. The framework is coherent and largely persuasive. But it stands in marked contrast with the classical civil-law doctrine of abuse of rights, especially as articulated by Louis Josserand.

For Josserand, abuse arose when the exercise of a right (even one formally valid) contradicted the purpose for which the right existed. No malice was required. A right could become abusive simply because it had drifted from its justificatory foundation and been transformed into an instrument of domination.

Seen from this tradition, the book’s notion of “abuse” feels intentionally narrow, centered on observable procedural behavior rather than on the deeper teleological question: Is the injunction sought consistent with the telos of the patent right? This is not a defect so much as a methodological choice, but it leaves unexplored a conceptual richness that could further illuminate the field.

Commensurate scope provides a measure; abuse of rights provides an orientation. A full remedial theory may ultimately require both.

Where the Book Excels: Structure, Discipline, and Judicial Usability

These critiques do not obscure the book’s genuine strengths. Dijkman navigates between two extremes: the rigidity of automatic injunctions and the amorphous balancing characteristic of American post-eBay jurisprudence. His reconstruction of U.S. case law incisively exposes how the “balance of hardships” often dissolves into a fog of impressionistic reasoning rather than a principled method.

In contrast, the proposed European test — grounded in the technical contribution of the patent — is both conceptually cleaner and more judicially feasible. The engagement with EU doctrine and the UPC’s remedial architecture is careful and astute. The writing is crisp, and the structure disciplined.

It is, in short, a substantial contribution at a formative moment for European patent remedies

The Deliberate Silences: SEPs, Interim Measures, and Damages

The author explicitly sets aside SEPs, interim injunctions, and damages — the areas where disputes are often the most fraught. His methodological reasons are legitimate, but the omissions inevitably limit the scope of the book’s immediate applicability.

Yet these silences do not diminish the conceptual value of the framework. Instead, they gesture toward future extensions: into standard-essential technologies, urgent relief, and the calibration of monetary remedies. The architecture is sturdy enough to bear those expansions.

Conclusion: A Work That Opens More Than It Closes

Dijkman’s Proportionality Test is rigorous, thoughtful, and disciplined. It offers a structured lens for thinking about patent injunctions at a moment when European courts (particularly the UPC) are seeking principled guidance.

But perhaps its most lasting contribution lies in the deeper question it quietly revives. By focusing so intently on commensurate scope, the book brings us back, indirectly, to Josserand’s perennial concern: Can a remedy be lawful yet unjust?
If so, where and how should courts draw that line?

The book provides a powerful method for measuring the reach of injunctions. The next step is to reconnect that measure to a normative compass capable of distinguishing the rightful exercise of a right from its potential drift toward sheer power.

A thoughtful, boundary-shaping work.

And perhaps the Rousseau cover is not merely decorative. In the dense jungle of legal rights, power, and restraint, the struggle between tiger and buffalo reminds us that beauty and violence often coexist, just as doctrinal coherence and remedial fairness must learn to do.