The term “uniformed services” means—The five uniformed services that make up the Armed Forces are defined in the previous clause :(A) the armed forces;(B) the commissioned corps of the National Oceanic and Atmospheric Administration; and(C) the commissioned corps of the Public Health Service.
The term “armed forces” means the Army, Navy, Air Force, Marine Corps, and Coast Guard.
The National Guard is a militia force and operates under Title 32 and under State authority. The National Guard was first formed in the Colony of Virginia in 1607 and is the oldest uniformed military force founded in the New World. The National Guard can be federally recognized as a reserve military force, becoming the National Guard of the United States which can be mobilized by the President to be under Federal authority through Title 10. The National Guard of the United States is managed by the National Guard Bureau, which is a joint activity under the Department of Defense , with a general in the Army or Air Force as its top leader. The National Guard of the United States serves as a reserve component for both the Army and the Air Force and can be called up for federal active duty in times of war or national emergencies .
Commissioned officers of NOAA and PHS wear uniforms that are derived from Navy uniforms, except that the commissioning devices, buttons, and insignia reflect their specific service. Uniformed officers of NOAA and PHS are paid on the same scale as members of the armed services with respective rank and time-in-grade. Additionally, PHS Officers are covered by the Uniformed Services Employment and Reemployment Act and the Service Members Civil Relief Act (formerly the Soldiers and Sailors Civil Relief Act).
Both uniformed service consist only of commissioned officers and have no enlisted ranks. Commissioned officers of the Public Health Service and of the National Oceanic and Atmospheric Administration can be militarized by the President of the United States. Statutory authorization to militarize the Public Health Service is under Title 42 U.S.C. (Based on rank, commissioned officers of the Public Health Service (USPHS) and NOAA can be classified as Category III, IV, and V under the Geneva Convention). The U.S. Coast and Geodetic Survey (a predecessor to NOAA) originally began commissioning its officers so that if captured while engaged in battlefield surveying, they could not legally be tried as spies. The Public Health Service (PHS) traces its origins to a system of marine hospitals created "for the relief of sick and disabled seamen" by the U.S. Congress in 1798; they adopted a military model of organization in 1871.