The driver for a group of Japanese tourists had little sleep after an 11-hour work day when the shuttle bus flipped, killing three passengers, according to a lawsuit filed on behalf of two of the 14 tourists.

Kei Maeda and his wife, Mai, were celebrating their first wedding anniversary when the crash left him partly paralyzed and her with a punctured lung and an eye injury, said a Utah lawyer filing the first lawsuit from the crash. It was filed against the driver, his bus company and a pair of tour organizers.

The driver, a Japanese citizen living in Las Vegas on a U.S. work and education visa, was due in a Cedar City court Tuesday on criminal charges stemming from the Aug. 9 crash on Interstate 15 near Cedar City.

Yasushi Mikuni was to appear on 10 felony counts of negligent driving under the influence, a misdemeanor charge of having marijuana residue in his system and logbook and unsafe lane-change violations.

Kei and Mai Maeda, both 29, returned to Japan last week after hospital stays in Utah. Their civil claims are the first, and possibly the only that will be filed because the other Japanese tourists left the U.S. unfamiliar with their legal rights, Scott Brown, the couple's lawyer, said Tuesday.

New allegations in the lawsuit filed Friday at federal court in Salt Lake City say Mikuni had driven the bus for 11 hours the day before the crash, taking an empty bus from the Salt Lake City suburb of Sandy to Las Vegas, then got less than seven hours of sleep. It also says Mikuni repeatedly dozed off and hit highway rumble strips and wasn't wearing eyeglasses as required by his driver license.

But Utah Highway Patrol investigators disputed another allegation in the lawsuit that Mikuni was speeding at more than 80 mph.

The investigators determined the bus was traveling around 75 mph, the speed limit, Utah Highway Patrol Sgt. Ryan Bauer told The Associated Press on Tuesday.

A speed of 80 mph would not have been significant and the limit on that stretch of the highway is set to be raised to 80 mph shortly, Bauer said. He said troopers found plenty of other reasons for negligence, but speed wasn't one of them.

An arrest warrant obtained by The Associated Press last month said that Mikuni had been smoking marijuana heavily for days before the deadly accident. But at the time the charges were announced, Bauer said the driver wasn't legally impaired. Instead, investigators believe fatigue was the major factor.

The lawsuit claims Mikuni smoked pot for three hours the night before the accident and had to sustain himself on energy drinks and nicotine gum while driving. But like the other claims, some of which appear to be taken from the police investigation, the lawsuit cites no attribution.

Bauer said Mikuna had a lawyer, but he didn't know the attorney's name. Officials at the Iron County jail where Mikuni was held briefly have no record of the lawyer. None was listed on a court docket, and 5th District clerks said they didn't know.

Other defendants named in the couple's civil case are Canyon Transportation Inc. of Sandy, which provided the Ford E350 shuttle bus, and tour organizers Western Leisure Inc. in Utah and Nippon Travel Agency in Japan.

Kei and Mai Maeda paid Nippon for a tour of Utah and Arizona canyonlands and Nippon contracted with Western Leisure of Midvale to set up the tour, according to their lawsuit. None of the companies have been charged by prosecutors.

The Utah lawyers representing Canyon Transportation, Dennis James and Brian Hess, didn't return phone messages Tuesday from the AP.