Apple has presented what it calls “shocking evidence” in its legal fight with OpenAI, saying a MacBook used by former employee Chang Liu revealed that Apple trade secrets were used while he was working for the ChatGPT maker.

In a new court filing, Apple said its initial forensic review of the MacBook found that Liu had downloaded a confidential Apple circuit schematic after leaving the company and later used it while working at OpenAI. Apple also claims the former employee used the circuit information to run simulations and worked with an AI agent on those simulations.“The MacBook further shows that in June 2026 and after learning they were the subject of an internal Apple investigation, Mr.

Liu and his OpenAI colleague Yu-Ting ("Alyssa") Peng exchanged messages in which he told her to have Apple-issued devices "restored" and to then "start using" them more. (Roffman Decl. 9 25, Ex. D.) Deliberately "restoring" and subsequently using a device is an example of "anti-forensic" conduct that overwrites forensic artifacts and evidence (Id.

26), such as evidence that would show what Mr. Liu did with misappropriated trade secrets,” Apple said in its filing.

Apple says former employee used trade secret at OpenAI

According to Apple's supplemental brief filed in a US federal court, Liu used an Apple trade-secret file in March 2026 while employed by OpenAI. The file contained a circuit schematic for a power-converter circuit, along with simulation data used to model how the circuit worked. Apple said the circuit was used in or being considered for Apple products and was highly confidential.The filing says Liu had downloaded the file from Apple's third-party cloud storage after leaving Apple for OpenAI in January 2026.

Apple says the file was downloaded on March 7.Then, on March 18, Liu allegedly used the circuit file to run a simulation in LTspice, an electrical engineering tool used to develop and study electronic circuits. The simulation produced at least three output files, which were later uploaded to Liu's iCloud from another computer, identified in the filing as a Mac Mini.

MacBook revealed former employee activity, Apple says

The MacBook became important to Apple's case because the company says files and information from Liu's iCloud account were later synced to the device.

Apple said this allowed investigators to determine what Liu had done on the Mac Mini, even though Apple says the Mac Mini itself has not yet been produced for examination.The filing also points to messages Liu allegedly sent around the same time. Apple says he described his work at OpenAI as involving an AI agent that learned how to run LTspice, examine the results and adjust a compensation parameter.Liu also reportedly said he was running these simulations as part of power-conversion development work and that the AI agent could complete work much faster after learning the process.

Apple says Chang Liu knew he still had access to its files

Apple is also challenging the claim that Chang Liu's access to its cloud storage was simply the result of accidental device syncing. The company says the MacBook showed that Liu continued accessing and downloading files from Apple's third-party cloud storage through the end of April 2026, weeks after his initial downloads.Apple argues that this contradicts the defence's claim that the downloads happened accidentally and were unknown to Liu.

Apple says OpenAI tools may also have an Apple connection

Apple's latest filing also alleges that Liu used a tool and related software packages at OpenAI with names identical to proprietary internal engineering tools used at Apple. The company says this was previously unknown to Apple and represents another potential instance of trade-secret misuse.In the filing, the iPhone maker further claims that more devices remain to be investigated, including the Mac Mini allegedly used to run the circuit simulations. Apple argues that the full extent of the alleged trade-secret use remains unknown.