In 1920, the Supreme Court applied the Supremacy Clause to international treaties, holding in the case of Missouri v. Holland, 252 U.S. 416, that the Federal government's ability to make treaties is supreme over any state concerns that such treaties might abrogate states' rights arising under the Tenth Amendment.
Age. To join the Military, you have to be at least 18 years old (17 with parental consent). As for the upper age limit, it depends on the Service and the program: Health Professions Scholarship Program (HPSP): 36 (for the Navy, you can be no older than 42 at the time you enter Active Duty, following your degree completionâunless you were granted an age waiver when you were recruited)
Quick Answer. The cutoff age to join the military differs in each branch. As of January 2015, it is 34 for the Army and Navy. It is 29 for the Marines, 39 for the Coast Guard and 27 for the Air Force. The limits may change based on prior or reserve service.