The United States Patent and Trademark Office (USPTO) director has ordered a reexamination of Nintendo’s “summon character and let it fight” Pokémon patent after widespread criticism from intellectual property (IP) experts.

Patent No. 12,403,397, also called the ‘397 patent, was initially granted to Nintendo without objection. Critics argue the claims are overly broad. The patent describes mechanics familiar to Pokémon games, where players summon creatures to battle and potentially capture them. Many other games, including Persona, Digimon, and even Elden Ring, feature similar mechanics depending on interpretation.

IP expert Florian Mueller said Nintendo “should never” have received this patent. Patent lawyer Kirk Sigmon mentioned in an interview that the claims “were in no way allowable.” The controversy has drawn scrutiny to both Nintendo and the credibility of the U.S. patent system.

USPTO Reexamination Initiated

John A. Squires, who became USPTO director in September, ordered the reexamination. He noted that “substantial new questions of patentability have arisen” regarding claims about controlling a player character, summoning a sub-character, and engaging in both manual and automatic battles.

Squires cited two older U.S. patent applications as prior art—one from Konami in 2002 and another from Nintendo in 2019. He stated that both could influence the patent’s validity. Mueller believes Squires acted due to “public outrage” over the patent and concerns about the reputation of the U.S. patent system. While the reexamination does not automatically revoke the patent, Mueller says the USPTO is now “highly likely” to do so. Nintendo has two months to respond.

Implications for Palworld Lawsuit

Nintendo and The Pokémon Company are pursuing legal action against Pocketpair over Palworld, which uses similar creature-summoning mechanics. The USPTO’s reexamination could weaken Nintendo’s claims, Mueller says.

Nintendo has faced setbacks in Japan as well. Last month, the Japan Patent Office (JPO) rejected one of Nintendo’s monster-capture patents, citing prior examples such as ARK (2015), Monster Hunter 4 (2013), and Kantai Collection (2013) to argue the patent lacked originality. Pocketpair’s Craftopia (2020) and Pokémon Go (2016) were also mentioned.

Since 2024, Nintendo has filed three divisional patents in Japan targeting Palworld: two for monster capture and one for riding characters. All derive from earlier 2021 patents, apparently designed to address alleged infringement. Pocketpair has adjusted Palworld’s mechanics in response, including changes to summoning Pals and gliding systems.

What Comes Next

Pocketpair continues to develop Palworld despite the lawsuit. Observers expect no major updates in the case until next year. Presiding Judge Motoyuki Nakashima of the Tokyo District Court’s patent division will decide on the matter. Mueller predicts that Nintendo’s chances of winning are diminishing.

At the Game Developers Conference (GDC) in March, John “Bucky” Buckley, communications director for Pocketpair, called the lawsuit “something that no one even considered.” He also addressed earlier, now-debunked claims that the studio misused AI or copied Pokémon models.

Former Capcom developer Yoshiki Okamoto sparked controversy in September after criticizing Palworld, drawing backlash from viewers who felt his comments were unfair. As the USPTO reexamination progresses, Nintendo’s patent and its ongoing litigation against Palworld remain under scrutiny, raising questions about the limits of intellectual property in gaming.