Jerry Seinfeld once said, “The stupidest thing is a helmet law, the point of which is to protect a brain that is functioning so poorly it's not even trying to prevent the cracking of the skull it's in.” But helmet laws for kids, who may not have considered their skulls as deeply as Jerry did, aren’t so dumb. That’s according to a new study in a publication from the Chocrane Collaboration, which is an international organization that evaluates health care research. The review looked at five studies of kids bike-helmet laws. One big 10 year study in California found that bike-related traumatic brain injury in kids dropped more than 18 percent after the state’s bike helmet law was enacted. A Canadian study looked at almost 10,000 bike related hospital admissions and found a 45 percent drop in childhood head injuries in provinces that passed helmet laws. Provinces without helmet laws also saw a drop in the same period, but only half as much. And three other studies found that helmet laws do indeed persuade kids to wear their helmets, with increases in compliance ranging from 45 to 84 percent.