Tesla is under criminal investigation by the U.S. Department of Justice due to the company’s claims its cars are self-driving, people familiar with the matter told Reuters. The investigation was launched following more than a dozen crashes, some fatal, that complicated the company’s self-driving disclaimer. CEO Elon Musk boasted last week that Tesla would release an upgraded version of “Full Self-Driving” software in the near future. The company’s website says a person in the driver’s seat “is only there for legal reasons.” The legal challenge follows a rollercoaster year for Musk of legal issues, including a battle over his effort to back out of his $44 billion Twitter takeover.