The sign is worthless for the purpose of shifting or avoiding liability. Same with signs in parking garages that say they aren’t liable for loss or damages. But each serves a more subtle purpose.
The sign alerts you to a risk. That gives you a chance to avoid the risk. In the case of a car following a truck, it’s not always a very meaningful chance. By the time you are close enough to read the sign, you probably have few safe options to avoid the injury.
In most cases one party cannot unilaterally disclaim liability.
OTOH, liability is not automatic. *E.g., *
First of all, you’d have to prove the driver or the owner was negligent. Was their conduct reasonable? If they violated a statute, you might be able to jump this hurdle by arguing negligence per se. But even then, you’d have to show that the violation was a proximate cause of your damages. As the quoted material indicates, this can be difficult to establish. First of all, the company could try to show that compliance with the statue would not have avoided your injury. As the plaintiff, you would also have to prove that the offending item came from the truck in the first place. And then you’d have to prove it came from the cargo area, and not, say, from a tire tread.
Not an open and shut case, for sure. Apparently, Matthew Alice of the San Diego Reader agrees with my analysis: What is the history/origin of the dreaded unity candle? | San Diego Reader