Final answer:
A soldier cannot refuse an Article 15 and demand a court-martial when serving in the land or naval forces, or Militia during time of War or public danger, following the provisions of the Fifth Amendment and various Supreme Court rulings.
Step-by-step explanation:
A soldier does not have the right to refuse an Article 15 and demand a trial by court-martial in certain circumstances. Specifically, this right is curtailed within the land or naval forces, or in the Militia, when they are in actual service during a time of War or public danger. These conditions are articulated in the Fifth Amendment of the U.S. Constitution and have been reaffirmed through various Supreme Court rulings, including the acknowledgment of the president's powers during times of military conflict to name persons as enemy combatants and to handle their detention accordingly, although due process must still be afforded for U.S. citizens.
Additionally, the writ of habeas corpus, a fundamental legal protection against unlawful detention, can also be restricted during times of war or national security threats. For example, the historical attempt by President Abraham Lincoln to try suspected Confederate sympathizers in military courts was a case where traditional civilian legal rights were bypassed, highlighting the government's historically broadened powers in such contexts.