Sometimes when caught in traffic, a driver in the right hand lane is tempted to pull out and drive up the shoulder until reaching an intersection where the driver hopes to turn off the congested road. However, California drivers should resist this temptation. For one thing, it is a recipe for legal trouble. Casually driving on the shoulder also disregards the true purpose of using this route.
California law makes it clear that drivers are to stick to the road if they want to get past another vehicle. If a driver seeks to get around traffic, the driver must do so safely without putting other motorists or pedestrians at risk. However, if no lane is available to make a pass, the motorist should remain on the road. State law does not allow a driver to veer off the designated main travel area of the road or the paved portion just to bypass a congested travel lane.
How Stuff Works explains that road shoulders are intended for emergency use only. A vehicle that suffers an abrupt breakdown may need to get off the road. Emergency responders use shoulders to get around congested traffic areas so they can reach accident areas in a timely manner. Ambulances need to reach wounded motorists and pedestrians, and police need to get to accident areas to file reports and redirect traffic.
Basically, using a shoulder can interfere with the lawful use of emergency vehicles. If there is a life threatening event that an ambulance needs to reach, your use of a shoulder might obstruct the progress of an ambulance where seconds could make a difference. An ambulance driver should not have to worry about dodging traffic while using the shoulder.
In the event there is an accident that does congest traffic, you might feel justified in using a shoulder anyway. However, it is still best to wait on the road. If the police can arrive on the scene quickly enough, perhaps by using the shoulder, they may redirect traffic around the accident. Police officers may even authorize use of the shoulder to get around a wreck.