In a subsequent legal showdown, the worker claimed he was deceived by Tesla's lawyer.

An employee departure from Dyson to Tesla in 2015 sparked a minor legal showdown and revealed to the latter company a document outlining the former's secret Project E plans.

Dyson engineer Pierre Pellerey reportedly began talks with Tesla recruiters before James Dyson invited him to join a team working on an electric vehicle project shrouded in a non-disclosure agreement, according to a Bloomberg review of court documents dating back two years.

Pellerey is said to have joined Dyson's EV development group while waiting for a solid offer from Tesla, which he later received. Dyson's legal team consequently sent a letter to the French national informing him that he could not work for Tesla for 12 months because his new employer is engaged in the "same type of business" as Project E.

After reporting the conflict, Tesla's associate general counsel allegedly demanded to see the letter as part of the company's due diligence. The worker complied, allowing Tesla to learn that Dyson planned to enter the EV segment and use unprecedented solid-state batteries to power its vehicle.

2017 Tesla Model S
2017 Tesla Model X

Tesla CEO Elon Musk has welcomed competition, hoping his company pressures the industry to help hasten a transition to electric vehicles. The company in 2014 opened its entire patent portfolio to competitors, taking inspiration from the open-source movement.

Dyson plans to spend $2.7 billion to bring an electric vehicle to market by 2020.