US DOT: Department of Transportation estimates that motorcycle helmets reduce the likelihood of crash fatality by 37 percent.

OFF THE WIRE
http://universe.byu.edu/node/15779%20Stricter%20helmet%20laws%20could%20reduce%20fatalities
By Kate Bennion-
The U.S. Department of Transportation estimates that motorcycle helmets reduce the likelihood of crash fatality by 37 percent.
However, laws requiring motorists to wear helmets receive some skepticism, especially in Utah.

Currently, 20 states and the District of Columbia have legislation covering all riders. Twenty-seven states have laws requiring some riders to wear helmets, usually determined by age. Illinois, Iowa and New Hampshire do not have state laws regulating helmet use.
Recent changes in helmet legislation and Congressional funding have prompted new laws across the nation — some loosening regulations, some increasing them. States such as Oregon are currently considering amending their helmet laws.
The National Highway and Traffic Safety Administration (NHTSA), part of the U.S. Department of Transportation, analyzed Florida’s motorcycle fatality following its legal change that allowed all riders over age 21 to go helmet-free.

According to the report, “Comparing the 30 months before and after the law change, there was an increase of 55 percent in the average annual number of motorcyclists killed.” Registrations also increased by an average of 33.7 percent.
Other states, such as Louisiana, went the other direction. Louisiana reinstated its helmet law and, according to the NHTSA, “there were approximately 9.4 fewer fatal and serious-injury crashes per month” as a result. According to the report, motorcycle helmet use increased by more than 40 percent.
Utah’s current motorcycle law requires riders under age 18 to wear helmets. However, some contend that age-based laws are unenforceable and ineffective.
In an analysis of census data comparing Utah to 38 states, Utah ranks 20th in fatalities per registered motorcycle, with a rate of .06 percent fatality per registered motorcycle. This is considerable because Utah has a shorter riding season than other, warmer states.
Although fatalities overall have decreased for the past two years, according to the Governors Highway Safety Association, in 2009 there were more than 32 motorcycle fatalities in Utah.
Strong individual freedom sentiments prevent Utah from passing a more restrictive law. In 2008, Neil A. Hansen sponsored a bill that would raise the helmet age to 21, which failed.

Organizations such as the Motorcycle Riders Foundation (MRF) or ABATE consider comprehensive helmet laws an infringement upon individual rights.