Most people consider the internet’s global reach an advantage. But for the Supreme Court on Tuesday morning, it was more of a headache.

The justices heard oral arguments in United States v. Microsoft, a high-profile case about digital privacy and law enforcement. At issue are dueling interpretations of an outdated federal statute that still governs how tech companies store and release private information to law-enforcement agencies. Those arguments took place against the backdrop of a broader debate about how to apply U.S. law to a supranational network of computers.

The underlying legal dispute began in 2013 when federal investigators obtained a warrant under the Stored Communications Act of 1986 for a Microsoft customer’s email account as part of a drug investigation. Some of the email account’s data are stored in the United States. But the emails themselves reside separately on servers inside a Microsoft data center in Dublin, Ireland.

Microsoft turned over the U.S.-based data but then asked the courts to quash the government’s request for the Ireland-based emails. The tech giant argued that Congress didn’t write the Stored Communications Act to apply within other countries and that, accordingly, the warrant request was improper. After the Second Circuit Court of Appeals agreed with Microsoft’s position, the Justice Department asked the Supreme Court to intervene.

Microsoft argued that the emails themselves—those particular ones and zeros inscribed on a hard drive in Dublin—are under foreign jurisdiction.

Both sides agree that the Stored Communications Act can’t be enforced in a foreign country. Where the two sides diverge is on whether Microsoft would have to take action overseas in order to acquire the emails in question. Since Microsoft can access them from its facilities in the United States, the government argues that the issue is entirely a domestic matter.