The California Supreme Court in Eli v. Murphy, (1952) 39 Cal.2d 598, established a non-delegable duty for highway common carriers. The court explained that highway common carriers are engaged in a business attended with very considerable risks to the public. The legislature's ability to ensure safety compliance would be hindered if the highway common carrier could escape liability by simply hiring independent contractors. Further, the public who is injured should not be deprived of the financial responsibility of those carriers who have been granted the privilege of conducting their business over the public highways. The court stated succinctly that a highway common carrier may not insulate themselves from liability for negligence occurring in the conduct of their business by engaging independent contractors to transport freight for them.

While the Eli decision was decided when the authority for highway common carriers was held by the Public Utilities Commission, the transfer of that authority to the DMV and California Highway Patrol in 1996 with the passage of the MCPPA does not alter that non-delegable duty. Section 34601 of the MCPPA classifies any person who operates a commercial vehicle as a "motor carrier of property." Motor carriers of property are then divided into two classes (1) a "for-hire motor carrier of property" defined as a motor carrier who transports property for compensation and (2) a "private carrier" defined as a motor carrier who transports only his own property.

On November 1, 2004, the California Appellate Court held in Hill Brothers Chemical Company v. Superior Court (Lorentsen), (2004) 2004 Cal.App. LEXIS 1843, that a "private carrier" is not subject to the non-delegable duty rule and was therefore not liable for the negligence of its independent contractors. The opinion in this case, however, reemphasized the non-delegable duty rule of "for hire motor carriers" citing the Eli case.