In which situation can the national government not be sued?

The national government cannot be sued without its permission due to the principle known as sovereign immunity. This legal doctrine protects the government from being sued unless it explicitly waives this immunity. This principle arises from the belief that the state cannot commit legal wrongs and thus cannot be sued for those wrongs without its consent.

In practical terms, the government has established certain statutes, such as the Federal Tort Claims Act in the United States, which outlines specific circumstances and processes under which it may permit itself to be sued. Consequently, individuals or entities wishing to bring a lawsuit against the national government must first ensure that a waiver of sovereign immunity applies to their situation.

The other scenarios, such as when a state seeks damages, a citizen files a lawsuit, or when operating in foreign affairs, do not fundamentally change the requirement for the government's permission to be sued. While there might be different legal considerations or specific laws that apply in those cases, the overarching principle of sovereign immunity remains the critical factor in determining when the government can be held liable in court.