William O. Douglas

“ The variety of requirements for equipment which the States may provide in order to meet their air pollution needs underlines the importance of letting the Coast Guard license serve as authority for the vessel to use, in all our ports, the equipment which it certifies. ”

“ Here the Coast Guard would be entitled to insist on different equipment. But it has not done so. The boats of appellant, therefore, have credentials good for any port; and I would not allow this local smoke ordinance to work in derogation of them. The fact that the Federal Government in certifying equipment applies standards of safety for seagoing vessels, while Detroit applies standards of air pollution seems immaterial. Federal pre-emption occurs when the boilers and fuel to be used in the vessels are specified in the certificate. ”

“ The requirements of the Detroit smoke ordinance are squarely in conflict with the federal statute. Section 2.2A of the ordinance prohibits the emission of the kind of smoke which cannot be at all times prevented by vessels equipped with hand-fired Scotch marine boilers such as appellant's vessels use. Section 2.16 of the ordinance makes it unlawful to use any furnace or other combustion equipment or device in the city without a certificate of operation which issues only after inspection. ”