The International Shoe revolution, which divorced service of process from territorial jurisdiction, paved the way for easy service of process abroad. But the revolution passed subpoenas by. The law of subpoenas remains strongly territorial. FRCP Rule 45 provides that subpoenas are to be served within the United States. This distinction makes sense if you conceive of a summons as a notice but a subpoena as a command. Anyway, as a general rule, you can’t serve a US subpoena on a witness abroad. And it’s not just because the foreign country might object or because of comity. It’s because US law puts territorial limits on where a subpoena can be served.

But there is an exception. Under 28 U.S.C. § 1783, a court can grant leave to serve subpoena on a US national or resident abroad. When someone calls me for advice about taking evidence abroad from a non-party, I always start by asking whether witness is an American. But even when the answer is yes, how useful is the statute?

First, a subpoena is undoubtedly a judicial document, and can my view at least, service of a subpoena is service of process in the strict sense. Therefore, if you are going to serve a subpoena abroad in a country that is party to the Hague Service Convention, you have to serve it by a method the Convention authorizes or at least permits. So if you are thinking about using a subpoena because the ordinary methods of judicial assistance in a particular country are difficult, then you may have service problems to consider.

Leaving service aside, there are some additional problems to consider. US courts have robust tools for enforcing their subpoenas, in particular the contempt power. But a US court has few if any options when the US citizen who is subject to the subpoena is abroad. Unless the citizen has property in the United States that the court can reach, what can the court do, really, if the citizen disobeys the subpoena?

Another problem: these days, when we take testimony abroad, we usually want, if possible, to do it remotely. Not always, but often. But if the witness is physically present in the foreign country, then some of the key the problems that cause us to look to the Evidence Convention come in to play. In particular, in many countries taking evidence without foreign government permission is illegal, or even criminal. Doing it pursuant to a US subpoena doesn’t solve the problem, and arguably makes it worse. In some cases, you might be able to solve the problem by taking the testimony at a US embassy or consulate. But in cases where you are going to need foreign government permission anyway, the use of the subpoena doesn’t get you very much.

A final problem: what about cases pending in state courts? The statute applies only to “courts of the United States,” i.e., federal courts.

In short, my experience has been that the statute is not as useful as it seems at first glance. Most often, the best advice is to proceed as though the witness were not an American, because whatever the strategy would be in that case is often the most likely to succeed anyway.