Veh. Code, § 21718

(a) No person shall stop, park, or leave standing any vehicle upon a freeway which has full control of access and no crossings at grade except:

(1) When necessary to avoid injury or damage to persons or property.

(2) When required by law or in obedience to a peace officer or official traffic control device.

(3) When any person is actually engaged in maintenance or construction on freeway property or any employee of a public agency is actually engaged in the performance of official duties.

(4) When any vehicle is so disabled that it is impossible to avoid temporarily stopping and another vehicle has been summoned to render assistance to the disabled vehicle or driver of the disabled vehicle. This paragraph applies when the vehicle summoned to render assistance is a vehicle owned by the donor of free emergency assistance that has been summoned by display upon or within a disabled vehicle of a placard or sign given to the driver of the disabled vehicle by the donor for the specific purpose of summoning assistance, other than towing service, from the donor.

(5) Where stopping, standing, or parking is specifically permitted. However, buses may not stop on freeways unless sidewalks are provided with shoulders of sufficient width to permit stopping without interfering with the normal movement of traffic and without the possibility of crossing over fast lanes to reach the bus stop.

(6) Where necessary for any person to report a traffic accident or other situation or incident to a peace officer or any person specified in paragraph (3), either directly or by means of an emergency telephone or similar device.

(7) When necessary for the purpose of rapid removal of impediments to traffic by the owner or operator of a tow truck operating under an agreement with the Department of the California Highway Patrol.

(b) A conviction of a violation of this section is a conviction involving the safe operation of a motor vehicle upon the highway if a notice to appear for the violation was issued by a peace officer described in Section 830.1 or 830.2 of the Penal Code.