Did you see the story recently on Today Show about safety chains. Very scary that some people are willing to risk accidents and injury. Safety chains make a difference.
They showed a real world demonstration of the difference safety chains make in an accident. In 1 test with safety chains, the vehicle towing the trailer was able to come to a safe stop. In another test, without chains, the trailer careened off the road and flipped end over end.
At the end of the Today Show segment, they reference NHTSA’s guide for safe towing. If you are unsure about the proper use of safety chains, I urge you to take a look at this guide.