Immunity from Jurisdiction

In one line

Immunity is not a denial that a court has jurisdiction; it is a bar on exercising it, because one sovereign does not judge another.

In the wording a student can write in an exam: immunity from jurisdiction is the principle that a State, its property and certain of its representatives are not subject to the jurisdiction of the courts of another State. It rests on the maxim par in parem non habet imperium, an equal has no authority over an equal, and on the sovereign equality of States. Sovereign immunity was formerly absolute and is now generally restrictive, being confined to acts of a governmental character. Diplomatic immunity is separate, is governed by the Vienna Convention on Diplomatic Relations 1961, and is functional in its justification.

The maxim, and what it rests on

Par in parem non habet imperium: an equal has no authority over an equal. If all States are sovereign and equal, the courts of one cannot sit in judgment on another.

Two further justifications are usually given. Non-intervention, since adjudicating on another State's acts is a form of interference in its affairs. And the practical conduct of relations, since a State whose ships, accounts and officials could be seized abroad could not function internationally.

The rule has always been in tension with a competing principle: that a person injured by a State should have a remedy somewhere. Every development in this branch of the law is an attempt to hold the two together.

Sovereign immunity: absolute, then restrictive

The absolute theory

Until the twentieth century a State was immune from the jurisdiction of another State's courts in all cases, whatever the nature of the act complained of.

That was tolerable while States confined themselves to governing. It became intolerable when States began to trade.

The restrictive theory

The modern position distinguishes two kinds of act.

Acta jure imperii, acts done in the exercise of sovereign authority: legislating, expelling a foreigner, running an army, granting a licence, issuing a passport. Immunity applies.

Acta jure gestionis, acts of a private or commercial character: buying wheat, chartering a ship, borrowing money, employing a gardener. Immunity does not apply, because in doing them the State has stepped into the market and should meet the market's law.

Why the change happened. State trading corporations, nationalised industries and State-owned shipping meant that a private party dealing with a State could be left without any remedy anywhere while a private competitor could be sued. The restrictive theory is a response to that inequality, not a weakening of sovereignty.

The difficulty it creates. How do you tell the two apart? Two tests compete. The nature test looks at the act itself: buying boots is a purchase, whoever buys them and whatever for. The purpose test looks at why it was done: buying boots for an army is a sovereign act. The nature test now generally prevails, because the purpose test would swallow the exception, since a State can attribute a public purpose to anything.