The latest proposal to again make helmet use mandatory for all Maine motorcyclists was presented by supporters Tuesday as a public safety issue and by opponents as a matter of personal freedom. Medical groups joined brain injury survivors and others in asking the Transportation Committee to pass the bill sponsored by Representative Paulette Beaudoin, the Biddeford Democrat whose similar bill in 2009 was rejected. The Maine Medical Association’s associate general counsel, Jessa Barnard, said helmets reduce the risk of head injuries by 69 percent and the number of deaths in motorcycle crashes by 37 percent.