Acquiescence by Coexistence and Serial Trademarks: The Italian Supreme Court Extends the Principle to Trademark Families

The recent judgment of the Italian Supreme Court, No. 12783 of 5 May 2026, marks an important development in trademark law because it extends the principle of acquiescence by coexistence to so-called trademark families, or serial trademarks. The significance of the decision is not merely procedural or case-specific, but systemic: the Court makes clear that a long and peaceful coexistence on the market may affect not only an individual sign, but also the distinctive core that characterizes a plurality of marks belonging to the same undertaking.

The ruling follows a European line of case law that had already developed the principle of coexistence as a limit on the possibility of challenging a later trademark when, despite identity or similarity between the signs, their prolonged coexistence has made the risk of confusion no longer current. The Supreme Court, however, takes the analysis one step further: it recognizes that the same logic must apply when coexistence concerns not a single mark, but a coherent system of signs built around a recurring distinctive element.

The Basis of Coexistence

To understand the scope of the ruling, it is useful to start from the principle itself. Acquiescence by coexistence is based on the idea that trademark exclusivity is not absolute in a static sense, but must be read in light of the actual market and the real conduct of businesses and consumers. If two identical or similar signs have remained on the market for a long time without the public actually becoming confused, it may be concluded that the essential function of the trademark has not been impaired.

In other words, a trademark does not live only at the moment of registration, but through the way it is perceived and used over time. The duration of coexistence therefore becomes decisive, because it can turn an originally conflicting situation into one that is now settled. This explains why case law has progressively recognized that the passage of time, if accompanied by good faith and effective coexistence, may produce a preclusive effect against later challenges.

The rationale is straightforward: if the market has already learned to distinguish the signs, there is no reason to protect rigidly a confusing risk that, in substance, no longer exists. Trademark protection remains strong, but it is brought back to its real function, namely indicating the commercial origin of goods or services.

From Individual Marks to Trademark Families

The most interesting novelty in the decision lies in the application of the principle to trademark families. The concept of a serial trademark assumes that an undertaking uses multiple signs linked by a recurring element, which the public recognizes as a distinctive feature of the same business origin. This may be a prefix, a suffix, a dominant verbal element, or a constant graphic structure used to differentiate product or service lines while remaining within the same brand architecture.

The Supreme Court observes that if coexistence is based on the loss of current risk of confusion, there is no reason to limit it to a single trademark when confusion has already been excluded with respect to the distinctive core of a family of signs. From this perspective, what matters is not only the sign in itself, but the overall effect that coexistence has produced on the trademark system as a whole.

This reasoning also makes economic sense. Businesses often build trademark families precisely to strengthen brand recognition, differentiate product lines, and foster consumer loyalty. If a central element of that system has long been shared by two different operators, and the coexistence has remained peaceful, the legal system cannot ignore that reality merely because the dispute concerns a plurality of marks rather than a single one.

The Role of Time in Confusion Analysis

One of the most important aspects of the judgment is the role assigned to time. Time is not merely a quantitative factor, but a genuinely qualitative one. Prolonged coexistence produces a stabilizing effect on perception: consumers become accustomed to the simultaneous presence of the signs and learn to distinguish them without linking them to a single source.

This is exactly where the risk of confusion disappears. At the outset, two trademarks may well be similar; however, if they have coexisted in the market transparently for years, the similarity gradually loses its harmful potential. The later sign no longer appears as an attempt to unfairly exploit the reputation of another, but as an element that has become independently established in consumer experience.

This shift is crucial. Trademark protection cannot be reduced to a snapshot of the moment of registration or first use. It must instead take account of the concrete dynamics of commercial circulation, where the meaning of signs evolves together with the public that encounters them. Coexistence by acquiescence is, in this sense, a technique for adapting the law to market reality.

Good Faith as a Key Requirement

The Court also reiterates that coexistence alone is not enough: the good faith of the owner of the later trademark is required. This requirement is particularly important because it prevents the principle from being used to legitimize opportunistic conduct or unfair commercial strategies. The preclusion applies only if the entrepreneur’s conduct is characterized by fairness and not if the later sign was adopted in order to exploit another party’s reputation or artificially create ambiguity in the market.

At the same time, good faith should not be understood too subjectively. The Supreme Court seems to give it an objective dimension, inferable from the context and the history of coexistence. If two trademarks have coexisted for decades without meaningful litigation and without appreciable interference in the public’s perception, that fact can be a strong indicator that the conduct of the owner of the later sign was proper.

This is especially useful in litigation, because it allows the preclusion argument to rest not on a purely abstract claim, but on concrete historical and documentary evidence: duration of use, territorial scope, continuity of commercial exploitation, manner of expansion, and the parties’ conduct over time.

The Case Before the Court

The case underlying the ruling is highly emblematic. The dispute arose from the application to register the mark “RTL 102.5 DOC” filed by RTL 102,500 Hit Radio Srl, which was later refused by the Italian Patent and Trademark Office following an opposition by RTL Group Markenverwaltungs GmbH. The central issue concerned the risk of confusion and association between the signs.

The Board of Appeal, however, overturned the administrative outcome, holding that the long coexistence of the “RTL” element in the respective trademark systems had eliminated the risk of confusion. In other words, the public had learned to distinguish the two commercial origins precisely because the marks had coexisted on the market for an extended period.

When the matter reached the Supreme Court, the Court had to address a highly relevant background fact: the existence of two trademark “families,” each built around a common core but historically developed by different entities. The decisive question was not so much whether the signs were abstractly similar, but whether, in light of their ultra-decennial coexistence, the confusion risk was still current. The Court answered no, and that is where the decision’s innovative force lies.

Practical Consequences for Businesses

From a practical standpoint, the ruling has important implications for both businesses and the professionals who advise them on trademark protection. First, it confirms that building a trademark family can be a robust branding strategy, but it requires consistency, continuity, and the ability to document the actual use of the sign over time.

Second, the decision gives significant value to historical evidence. In disputes involving serial trademarks, it is not enough to invoke the existence of a common element or the notoriety of the mark: one must show how that sign system has been used, perceived, and consolidated. Commercial documents, advertising materials, campaigns, registrations, and any evidence useful to reconstruct long coexistence will therefore be particularly important.

Third, the ruling shows that trademark enforcement cannot be based only on abstract formal priority. A right holder who has tolerated the coexistence of similar signs for a long time may now face a substantial limit on its exclusive claims, especially if that coexistence has produced a stable market structure.

Systemic Significance

The judgment fits within a broader evolution of trademark law, which is increasingly attentive to the actual function of signs in the market. A trademark is not just a property title; it is also a tool of economic communication that exists in the relationship between undertaking and consumer. If that relationship has been stabilized over time through two distinct but coexisting signs, the law must take that into account.

From this perspective, coexistence by acquiescence offers a balanced solution: it protects the owner of the earlier mark, but prevents protection from being invoked in a formalistic way when the market has already moved beyond the stage of potential confusion. Extending the principle to trademark families strengthens this logic, because it avoids allowing fragmentation of the trademark system to become an artificial obstacle to the stabilization of already consolidated commercial relations.

In short, the Supreme Court seems to suggest a less rigid and more market-oriented view. Reputation, coexistence, and consumer perception become central elements of the analysis, alongside the literal or conceptual comparison of the signs.

Conclusion

Judgment No. 12783 of 2026 is an important milestone in Italian trademark law. The Court clarifies that acquiescence by coexistence does not stop at the individual trademark, but may also extend to a family of signs when the common distinctive core has coexisted for a long time with another sign in a peaceful and good-faith manner.

The underlying message is clear: trademark law cannot ignore time. When the market has stabilized its perception and the risk of confusion has disappeared, protection cannot continue to operate as if the conflict were still current. For businesses and practitioners, this decision calls for careful reflection both on registration strategy and on the management, over time, of coexisting commercial signs.