Final ruling reinforces the limits on the use of registered trademarks and reignites the debate over the protection of intangible assets in Brazil
Brazil’s Superior Court of Justice (STJ) has definitively upheld the exclusive protection of the INSULFILM™ trademark, bringing to an end a legal dispute involving Renault do Brasil and the automaker’s dealerships. The case became final and unappealable on May 25, 2026, after all appeals filed by the vehicle manufacturer had been exhausted.
The controversy arose from the use of the term “Insulfilm” in promotional campaigns for the sale of new vehicles. In the offers, the window film was advertised as a complimentary benefit to consumers, although, according to the courts, products manufactured by other companies were actually installed.
During the proceedings, Renault argued that the term had become a generic expression used to designate automotive window films, a legal theory known as trademark genericide. However, the STJ rejected this argument.
In her opinion, Justice Nancy Andrighi concluded that widespread popular use of a term is not sufficient to deprive the owner of a duly registered trademark of its legal protection. The ruling reinforces that the notoriety of a brand does not authorize third parties to exploit its commercial reputation to promote products or services without authorization.
With the final judgment, the judicial discussion has been concluded and the case will now return to the São Paulo State Court for the enforcement phase and the determination of damages.
More than a dispute between companies, the case broadens the debate over intellectual property protection in an economy increasingly driven by intangible assets, reputation and market differentiation.
According to INSULFILM do Brasil, the decision reaffirms the importance of legally protecting intangible assets in a scenario in which trademarks represent a significant portion of companies’ economic value.
“The ruling reinforces a fundamental principle of intellectual property: companies cannot appropriate the reputation built by others to boost their own businesses. Trademark protection is essential for legal certainty, fair competition and consumer trust,” says Francisco Fino, controlling partner of Insulfilm.
According to Thiago Bernardo, partner at BCMS Advogados, the importance of the decision lies in its rejection of a recurring argument often raised in disputes involving highly renowned brands.
“This case is considered landmark because it addressed Renault’s argument that the INSULFILM™ trademark had undergone degeneration and become a common designation for automotive solar protection films,” he says.
According to the attorney, the STJ upheld the understanding previously adopted by the São Paulo State Court, confirming that the trademark remains entitled to legal protection.
“The Court emphasized that the popular use of the term ‘Insulfilm’ as a generic reference to protective window films is not enough to characterize the loss of distinctiveness of the trademark. The incorporation of the name into everyday vocabulary does not, by itself, transform it into a generic market expression, particularly because the trademark owner continues to regularly exercise its trademark rights and commercially exploit the brand, circumstances that preserve its exclusivity,” he explains.
For Bernardo, the ruling reinforces an important precedent for companies investing in the development and maintenance of intangible assets.
“Even if the word ‘Insulfilm’ immediately evokes a particular product, the sign remains protected by trademark registration and cannot be used without authorization from its owner. This is an important decision for intellectual property protection and for the legal certainty surrounding historically established brands in the Brazilian market,” he concludes.
The decision is also particularly relevant at a time when discussions involving intellectual property extend beyond the physical world and increasingly reach digital environments, where brands, reputation and corporate identity have become strategic assets for organizations across all industries.
ABOUT INSULFILM™
Present in the Brazilian market since 1986, INSULFILM™ is a registered trademark associated with technical films applied to vehicles, buildings and corporate environments. Over nearly four decades, the brand has consolidated its market presence through a system involving technical specification, certified installation, quality control and performance validation. Today, INSULFILM™ is recognized as one of the most traditional and established brands in Brazil’s glass film industry.
