This guide sets out the law of commercial motor vehicle liability for plaintiffs' counsel, defense counsel, carriers, and safety professionals. Part 1 maps the statutory and regulatory architecture in Title 49 and identifies which regulation supplies which duty, while Parts 2 through 5 work through driver qualification, hours of service and the electronic records that now prove compliance, vehicle maintenance and cargo securement, and controlled substances testing including post-accident windows. Part 6 develops the theories of carrier liability beyond respondeat superior and the admission gambit that can eliminate them. Part 7 addresses brokers, shippers, owner-operators, and the preemption question dividing the circuits. Part 8 covers insurance architecture and the MCS-90 endorsement, and Part 9 treats preservation and spoliation under Rule 37(e). Parts 10 through 14 address damages, defense strategy, carrier compliance programs, a worked example, and the questions that recur in every case.