The driver of a van and a tour operator have been sued over a crash in Utah that killed three Japanese tourists and injured 11 others.

The Salt Lake Tribune says the lawsuit filed Friday in federal court claims passenger Kei Maeda has suffered incomplete quadriplegia since the Aug. 9 crash. Maeda was among 14 tourists in the vehicle when it crashed near Cedar City during a trip from Las Vegas to Bryce Canyon National Park.

The lawsuit claims driver Yasushi Mikuni had THC in his system, indicating marijuana use, when he fell asleep at the wheel. Investigators, however, say he was not impaired.

Mikuni has been charged with negligent driving under the influence. The operator has not been charged.