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)
You also cannot enlist in the active-duty Navy, which has a maximum entrance age of 34 years, or the active-duty Air Force and Coast Guard, which have a maximum entrance age of 27 years. The Air Force Reserve has a maximum entrance age of 34 years.ther opportunities for enlistment if you are 38 years old include the Navy Reserve, which has a maximum entrance age of 39 years; the Air Force National Guard, which has a maximum entrance age of 40 years; and the Coast Guard Reserve, which has a maximum entrance age of 39 years.