• Helmets that are not Department of Transportation-approved should not be worn by motorcycle riders.Chris Rady/Brand X Pictures/Getty Images
  
  All too often, lives could be saved and the effects of accidents lessened if motorcycle riders would only wear helmets. However, many states do not require that helmets be worn by all riders and passengers, giving motorcyclists the freedom to ride without helmets if they so choose. Regardless of whether people wear them, all motorcycle helmets sold in the United States are required by federal law to meet several standards set by the U.S. Department of Transportation. Both testing and labeling are required.
  
  

Impact Test

• The U.S. Department of Transportation mandates an impact attenuation test, whereby the helmet is dropped from several feet onto a series of four anvils. The helmet shall hold up to the impact of all four anvils to pass the test.
  
  

Penetration Test

• The penetration test involves dropping a guided test striker onto the helmet. The striker hits the helmet several times during this stage of the tests. The striker is dropped from 118.1 inches and weight 6 pounds, 10 ounces. The striker also must have a minimum hardness of 60 on the Rockwell scale.
  
  

Retention System Test

• A retention system test is done with static tensile loads. The helmet is placed in a retention assembly on rollers; test loads of 50 pounds and 250 pounds are then applied to see if the helmet can handle the stress of them.
  
  

Labeling

• The DOT has strict labeling requirements for helmets. Approved helmets shall have a label that clearly states the manufacturer's name, the helmet model, its size, when it was manufactured and the DOT symbol. The label also must identify what the helmet is made of, must warn that it can be seriously damaged if some substances are applied to it and must warn that its owner shouldn't modify the helmet.
  
  

Unapproved Helmets

• Some riders may want to ride with a helmet because of the way the helmet looks -- for instance, a helmet with a spike in the top or an Army combat helmet, two styles which have been popularized in the movies. The U.S. DOT, however, cautions that such helmets do not afford proper protection, perhaps hardly any at all. Only DOT-certified helmets should be worn by riders.