The Federal Aviation Administration (FAA) (defendant) issued a series of advisory circulars regarding the testing requirements of airport-runway light bases. There are two types of light bases—adjustable and fixed. The FAA required both types of light bases to pass a so-called torque test. Through one of its advisory circulars, the FAA changed the requirements related to light bases and no longer required fixed light bases to pass the torque test. In a later advisory circular, the FAA imposed more stringent testing requirements on adjustable light bases. The FAA solicited comments for a subsequent advisory circular related to the new testing requirements from several companies that made adjustable light bases. Safe Extensions, Inc. (plaintiff) manufactured adjustable light bases, but it was not one of the companies from which the FAA sought comment. The companies that did provide comments argued that the test was unfair because it targeted only adjustable light bases even though neither adjustable nor fixed light bases could pass the new torque test. The companies also claimed that there had never been a safety issue with adjustable light bases in 20 years of use. The FAA issued the advisory circular with the new testing requirements, providing only a brief explanation for its decision and stating that the variability inherent in installation of adjustable light bases necessitated closer attention with respect to anti-rotational features. Safe Extensions filed for review of the latest advisory circular in the United States Court of Appeals for the District of Columbia Circuit, claiming that the FAA had acted arbitrarily and capriciously by singling out adjustable light bases.