Most people know it's against the law to talk on a cellphone while driving a car.
But what about looking at a GPS map on a phone or adjusting music with one?
A Fresno County appeals court answered the question in a recent ruling that appears to expand restrictions on cellphone use.
The three-judge panel upheld a ticket issued to Steven Spriggs, a Fresno State University fundraiser, who pulled out his phone while stopped in traffic to study a map.
The court found Spriggs was guilty of distracted driving because he was using his hands to operate the device.
It said the distraction would exist "whether the wireless telephone was being used as a telephone, a GPS navigator, a clock or a device for sending and receiving text messages and emails."
The ruling is only binding in Fresno County, but it is likely to be persuasive elsewhere, said Sonoma County Traffic Court Commissioner Lawrence Ornell, who found the court's analysis to be "sound."
"This is the first case on this," Ornell said. "It takes a definite position. A bright-line ruling, as they say in the law field."
But police agencies in Sonoma County said it may have little practical effect. They already give the $162 tickets to anyone operating a cellphone while driving a car.
"It doesn't matter what you are using it for," CHP Officer Jon Sloat said. "The way we look at it is, if it's in your hand and you are on the roadway, we make an enforcement stop."