Under Thailand’s Patent Act B.E. 2522 (1979), any person may raise the invalidity of a patent as a matter of defense. However, the right to initiate court proceedings to cancel a patent is reserved exclusively for an “interested person” or the public prosecutor. This distinction between merely challenging validity and initiating judicial revocation proceedings has given rise to a significant body of Supreme Court (Dika) jurisprudence interpreting who qualifies as an “interested person” under the Patent Act.
Statutory Framework
Section 54 of the Patent Act provides that any invention patent granted not in compliance with the patentability requirements will be invalid, and that a petition to cancel such a patent may be submitted to the court by any “interested person” or the public prosecutor. Section 64 mirrors this provision for design patents, and section 65 novies extends the same framework to petty patents.
However, none of these provisions defines the term “interested person,” leaving its interpretation to the courts.
Supreme Court Interpretation
The Thai Supreme Court has developed a consistent body of case law establishing that an “interested person” must be someone directly affected by the existence of the patent—not simply any member of the public.
In 1989, the court found (Dika No. 2670/2532) that a party whose intended use of the patented technology was still in a preparatory stage—before actual manufacturing had commenced—did not qualify as an interested person. However, in 2009 the Supreme Court further elaborated (Dika No. 2906/2552) that an interested party is one whose rights to utilize the invention are restricted by virtue of the patent, such as a manufacturer or producer whose operations are directly impacted by the patentee’s exclusive rights.
In the 2008 case of T.M. Grating Steel Co., Ltd. v. Billion Mass Industry Co., Ltd. (Dika No. 974/2551), where the plaintiff had been subjected to criminal charges for alleged patent infringement by the defendant, the Supreme Court found sufficient standing, as the plaintiff was directly and concretely harmed by the enforcement of the patent in question.
Another instructive decision (Dika No. 3787/2555) came in 2012. The plaintiff in the case was a company that imported and distributed healthcare and food supplement products. It had purchased foam books for children to use as promotional giveaways bundled with its food supplement products, and the petty patent holder sent a cease-and-desist letter alleging infringement. The plaintiff then filed a court petition seeking to invalidate the petty patent under section 65 novies. Although the Intellectual Property and International Trade Court, as the court of first instance, found sufficient standing, the Supreme Court, however, held that the plaintiff was not an interested person. The court reasoned that the plaintiff’s core business was importing and distributing healthcare products—it had no need to use the patented process, nor did it manufacture, sell, or import foam books produced by the patented method. Moreover, the court held that giving foam books away for free as promotional items did not constitute “selling” under the Patent Act; therefore, the petty patent did not directly impede the plaintiff’s ordinary business operations. Notably, the court observed that the plaintiff would be able to assert the invalidity of the petty patent as a defense (as allowed of “any person” under the Patent Act) should the petty patent holder initiate infringement proceedings.
In 2018, the Supreme Court ruled (Dika No. 4225/2561) that a director and shareholder of a company alleged to have infringed a design patent was not an interested person entitled to file an invalidation petition under section 64 of the Patent Act, because the individual’s claimed damages were derivative of the company’s harm, and the individual had no direct interest in the patent separate from the juristic person.
Similarly, in 2023, the Supreme Court denied standing (Dika No. 67/2566) to the Department of Land Transport, a government agency, after it sought to revoke two petty patents relating to vehicle data-reading devices. The court reasoned that although the agency had regulatory oversight functions, it did not produce, use, sell, or import the patented products and therefore lacked the requisite direct interest.
Practical Implications
These decisions make clear that questions of whether a party has standing to proactively petition for cancellation of a patent are fact-intensive and require a direct nexus between the challenger’s commercial or exploitative activities and the exclusive rights conferred by the patent. Parties contemplating an invalidation action should be prepared to demonstrate concrete evidence that their manufacturing, commercial, or import activities are impeded by the patent’s existence. A merely regulatory, administrative, or derivative interest—such as that of a shareholder, company officer, or government regulator—will not suffice.
Practitioners should also note that while standing to file a petition for cancellation is restricted, validity may still be raised as a defense by any person in infringement proceedings. This dual-track framework provides defendants in patent infringement cases with a reliable mechanism to challenge patent validity, even if they might not independently qualify as “interested persons” to initiate standalone revocation actions.
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