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The handsfree law CVC 23123, applies to motor vehicles.
On the plus side, at least it's gotten people talking about distractions of all kinds.
The consequences of distraction are still illegal. For example, unsafe lane changes, running stop signs, etc.
You don't actually have to hold a cell phone to your ear, or be drunk, to do something stupid/dangerous/illegal while driving. Even perfectly sober, alert people do stupid/dangerous/illegal things while driving.