(Olympia, WA) -- Washington State Attorney General Bob Ferguson says Seattle's sales tax on guns and ammunition is legal. Ferguson, who's a Democrat, issued an opinion saying the tax, which took effect on January 1st, complies with state law. Ferguson filed a friend-of-the-court brief Monday with the state appeals court regarding the National Rifle Association's challenge to a King County Superior Court ruling. The NRA claims the 25-dollar-per-gun tax charged to gun sellers and the two-to-five-cent tax per round of ammunition violate a state law that bans cities from regulating firearms.