The current stiff rear underride guard standards are a safety compromise that do not protect all sizes and weights of current vehicles. They ultimately are too stiff for small vehicles or are too weak for large vehicles. Only energy-absorbing guards provide protection for most sizes and weights of current vehicles and modern designs are cheap and simple to implement. Any new rear underride guard standard should be an energy-absorbing guard standard to reflect state-of-the-art research and interact properly with modern vehicle designs.

In 2005, the U.S. still allows deadly guillotine guards on the backs of all single-unit trucks and many specialty trailers, including all trailers built prior to 1998. Is this 1952 safety regulation the best the U.S. government can achieve after 53 years? These false guards do not prevent underride even at low speeds and cannot be considered state-of-the-art in civil litigation.

Brazilian underride guard regulation that correctly exceeds unsafe U.S. and European Standards

The new Canadian Rear Guard Regulation

Canadian rear underride guard tests and recommendations in PDF format.

Penn State simulated car-truck crashes with varying guard heights

Australia - MUARC underrun guard recommendations