The Supreme Court today is hearing oral arguments about a Washington state law regulating oil tankers that imposes safety and environmental guidelines more stringent than federal ones. Intertanko, an organization representing 75 percent of the world’s tanker companies, is asking the court to overturn the law, which was enacted in response to the 1989 Exxon Valdez disaster in Alaska. The Clinton administration is siding with the oil industry, agreeing that states in this case have no authority to enact regulations tougher than federal ones. Washington state, meanwhile, is supported by 30 other states in its contention that tougher tanker laws are needed to help prevent major oil spills. Lower courts so far have backed Washington state, saying a 1990 federal law explicitly allows tougher state controls. Enviro groups, which often side with the feds against states’ rights, are of course backing the states this time around.