The most serious charge - attempted second-degree murder - carries a maximum 30-year sentence, according to court documents.
Washington County Assistant State's Attorney Arthur Rozes told France the case "is a classic case of road rage.
"He was enraged that someone wouldn't let him pass on Interstate 70," Rozes said. He said Johnson did not realize "there was a sleeping woman in the passenger seat" of the 2003 Chrysler PT Cruiser.
When given a chance to speak Tuesday, Johnson, appearing in court from the Washington County Detention Center via closed circuit television, told France, "What happened yesterday was road rage, but it wasn't all my fault. I really was defending myself ... I am glad - truly glad -that no one was hurt. I really wish this wouldn't have happened."
According to charging documents, Johnson had been following Kyle Hitchcock, the driver of the PT Cruiser, "very close in the left lane, then moved to the right lane and began passing him," at which point he fired "several shots" at the car.
Johnson told police after his arrest that he fired the gun "until the gun stopped firing," which probably was two or three rounds, but could have been as many as five, according to court documents. One empty 9 mm shell casing was found on the floor of his Suburban, and two shell casings were found where the shots were fired, at about the 22-mile marker of the eastbound lanes, police said in charging documents.
Police learned of the incident after a trooper stopped to check on the PT Cruiser, which was disabled and dented from gunfire in the median of the highway, according to court documents.
Rozes said Johnson has past convictions in Maryland for assault with a deadly weapon with the intent to injure and in California for robbery.
France set a preliminary hearing in District Court for Johnson on July 18.
