The U.S. Occupational Safety and Health Administration (OSHA) is the agency that establishes rules for safety in the workplace. Although many of the rules guiding the trucking industry are established by different agencies, OSHA offers some guidance for trailer safety under §1910.178. This includes some guidance regarding when and how to use jack stands in the loading and unloading of a trailer.
OSHA establishes rules for tractor trailers under its guidelines in §1970.178. However, the guidelines are broad, guiding use by all "fork trucks, tractors, platform lift trucks, motorized hand trucks, and other specialized industrial trucks powered by electric motors or internal combustion engines." There are other federal agencies that guide rules for tractor trailers. The agency that is most likely to specifically guide standards for tractor trailers on American highways is the U.S. Department of Transportation's Federal Motor Carrier Safety Division. Many of the most germane standards for tractor trailers are established by this agency.
Jacks are used when loading and unloading a tractor trailer. Also called "trailer jacks," the goal of the jack is to prevent the up-ending of a trailer during loading and unloading. They are designed to work with other safety equipment to raise and stabilize the trailer. In doing so, they prevent not only up-ending of the trailer, but slight tips that can injure workers who are loading or unloading the trailer. While the jack is in place, the trailer is immobilized and typically is raised off the ground.
OSHA requires that trucks be immobilized during the loading and unloading process to ensure safety of the workers. Standards include setting brakes, setting wheel blocks, and using a jack stand. In addition, OSHA has established a standard that requires "mechanical means" to be used to ensure that a truck is unable to move while being loaded and unloaded. While at the loading dock, OSHA states that, "A positive mechanical means to secure trucks or trailers to a loading dock" can be used provided that effectively immobilizes the vehicle. This standard would include such mechanical devices as jack stands.