Is it possible to prosecute the president if a loved one is killed during an illegal war?

Under current United States law, it is extraordinarily difficult, and likely impossible, for private individuals to successfully prosecute or sue a sitting or former president for the loss of a loved one in an "illegal war."

Recent Supreme Court rulings have solidified broad immunity protections for a president's official acts, which include military orders.

Here is a breakdown of the legal, constitutional, and practical constraints:
1. Presidential Immunity
Criminal & Civil Shield: The Supreme Court has established that presidents have absolute immunity from civil damages for official acts (Nixon v. Fitzgerald) and broad immunity from criminal prosecution for actions within their constitutional authority, including military command (Trump v. United States).

2. The "Illegal War" Argument
Political Question Doctrine: US courts typically view the legality of military conflicts as "political questions" for Congress and the President, not the judiciary. Actions taken without formal declarations, often justified by Authorization for Use of Military Force (AUMF) acts, are rarely actionable in domestic courts.

3. International Law & Alternative Avenues
Limited Reach: While international bodies like the International Criminal Court (ICC) can address war crimes, the US is not a member, shielding officials from direct prosecution.

Liability Down the Chain: While the president has strong immunity, legal liability for violations of the laws of war may still apply to lower-level commanders and personnel.

In summary, the Supreme Court's recent interpretations make it legally, if not functionally, impossible for private citizens to successfully prosecute a president for wrongful death in an "illegal war".