High-visibility protective garments are required for right-of-way workers, flaggers and adult crossing guards in a the Manual on Uniform Traffic Control Devices (MUTCD). These garments must be compliant with ANSI/ISEA 107, the American National Standard for High Visibility Safety Apparel and Headwear.
Public safety workers such as law enforcement, firefighters and other emergency responders have the option of wearing high-visibility vests specifically designed for their use, and compliant with ANSI/ISEA 207, American National Standard for High-Visibility Public Safety Vests.
A December 2009 revision to the MUTCD mandates that public safety vests be labeled as compliant with the 2006 version of the standard or a subsequent revision. ANSI approved the revised standard in 2011, and ISEA sought an interpretation from Federal Highway Administration (FHWA) that garments meeting the new standard would be acceptable, noting that the requirements of the two standards for daytime and nighttime visibility are essentially the same. FHWA agreed, and issued an official interpretation stating that ANSI/ISEA 207-2011 is equivalent to the 2006 version, and that garments labeled as meeting the 2011 standard would be in compliance with MUTCD requirements.
Learn more about the standard here.