In a patent infringement lawsuit filed by Toshiba Corporation against four Taiwanese companies, the IP Court rendered an interim judgment (2014-Ming-Zhuan-Su-48) in October 2015, holding that three of the asserted NAND flash memory products manufactured and sold by the defendants (Model Numbers A5U1GA31ATS-BC, A5U2GA31BTS-BC and A5U4GA31ATS-BC) had infringed Toshiba's patents. The IP Court also confirmed that Toshiba's patents should be valid.

Toshiba filed the lawsuit based on two invention patents (Patent 154717 and Patent I238412). In the interim judgment, the court concluded that the technical means, functions and results of the three NAND flash memory products were substantially identical to the asserted claims of Patent 154717. As a result, infringement was found under the doctrine of equivalents. In addition, according to the technical features stated in the data sheets of the three products, the court determined that the products constituted literal infringement on the asserted claims of Patent I238412.

The court is in the process of determining damages.