The SC Court of Appeals held that UPS was protected under a federal statute from being sued by a plaintiff for a negligent act. The main question in this case is whether or not the particular federal statute (FAAAA) actually preempted the state tort claim.
This is probably an oversimplification, but hopefully it is somewhat correct...
-Federal law trumps state law under the Supremacy Clause:
-State common law (tort law) is included in this, and thus is also trumped by federal law
-Was the negligent act by UPS considered an act that is regulated by the FAAAA or was it outside the scope and on the "periphery" of the FAAAA?
The court held that the act that the plaintiff was suing for was actually an act regulated by the FAAAA and thus preempted by federal law. Summary judgment granted.
You can see how this same type of analysis will apply to similar plaintiffs attempting to sue a defendant who is engaged in a federally regulated industry.