Transporting horses in double-deck trailers would be banned nationwide under legislation introduced into the U.S. Senate by Illinois Senator Mark Kirk on June 27.

Some animal welfare advocates have long considered double-decker horse trailers inhumane because their configuration is not high enough for the animals to stand with their heads extended to normal postural height. According to National Agricultural Data Base recommendations, horse trailers should be between seven and eight feet high and six to eight feet wide. However, according to the Animal Welfare Institute, the average double-deck trailer ceiling ranges in height from 4 feet, 7 inches to 5 feet, 11 inches. Interstate highway regulations requiring a 14-foot minimum vertical clearance under overhead structures precludes double-deck transports from being high enough to properly accommodate equines.

If passed, S.1281, the Horse Transportation Safety Act of 2011, would prohibit the transport of horses in a motor vehicle containing two or more levels stacked on top of each other to or from any point within the U.S. and its territories. Violators could face fines of up to $500 for each horse contained in the trailer.

Donna Ewing, president and founder of the Hooved Animal Rescue and Protection Society, said the bill is necessary to improve equine transport safety: "The transport of horses in double-deck trailers is unacceptable because when rollover accidents happen they are horrific. We owe it to the horses to be as humane as possible