VIAVI Solutions of the U.S. filed a patent infringement lawsuit in the Seoul Central District Court against O, which supplies optical filters for near infrared sensors used in domestic 5G mobile phones. VIAVI Solutions also filed an injunction to patent infringement in the International Trade Commission (ITC) in the US and in the California District Court against L, which exports mobile phones to the US, and O, which is the supplier of the mobile phone parts. AIP, which represented O, claimed a patent invalidation trial against the registered patent in Korea owned by VIAVI Solution. After an intense argument on the major technical issues such as the manufacturing process of hydrogenated silicon, optical functions, and filter design with Kim & Chang, which represented VIAVI Solutions, the Patent Tribunal decided an invalidation on all of the 19 claims (2 claims were canceled by the amendment) based on unclear description of the patent specification and lack of inventive step. This decision to invalidate the patent became the first obstacle for VIAVI Solutions which was in the process of negotiation with the optical filter manufacturer in many countries around the world, holding out patent litigation as its leverage. After winning on this patent invalidation lawsuit, O was able to strengthen its position in the ITC lawsuit in which L was omitted by a separate patent negotiation and by reaching an agreement with VIAVI.