Can you look at the map on your phone while driving?

In the old days, it wasn't uncommon to drive with a map on your lap or on the dashboard or in the passenger seat. Today, cell phones have great map apps useful for navigation. But it's illegal to be looking at your cell phone while driving... Thus, you can't use your map app while driving, according to the Fresno County Appellate Division in today's opinion (in gloriously retro courier font):

Public concern about the dangers of distracted driving has led to legislation that limits the use of cellular phones and electronic communications devices while driving. The drive behind this legislation was the concern about the interference with the driver‟s attention caused by the physical aspects of using these devices. This case requires us to determine whether using a wireless phone solely for its map application function while driving violates Vehicle Code section 23123. We hold that it does.

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Because it is undisputed that appellant used his wireless telephone while holding it in his hand as he drove his vehicle, his conduct violated Vehicle Code section 23123, subdivision (a).