Who Can Challenge Patent Validity As An “Interested Person” Under Thailand’s Patent Act?

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.