While prosecutors and big tech companies clash over access to digital data in the United States, the issue also has broad resonance overseas, leading some countries to demand that data be stored within their own borders. Prosecutors abroad also complain of obstacles to conducting probes of criminal suspects using U.S.-based webmail.
"Eight of the 10 most popular web services and web sites in almost every country in the world, with few exceptions, are American," said Andrew K. Woods, a professor at the University of Kentucky College of Law. He added that foreign requests to companies like Microsoft and Google for email disclosure have soared.
"The cops in Brazil and the cops in India and the cops in France, all of the cops in the world, want to issue normal evidence orders in accordance with local law and they are frustrated or stymied by American rules," Woods said.
Woods cited a hypothetical case in which a Londoner is a suspect in the murder of a fellow Brit, a crime investigated by local police.
"Everything about that case is British," Woods said, but police "cannot go to Google and compel Google to give them content of the suspect's email account. They have to go through the mutual legal assistance process. That is not only slow it is also an affront to British sovereignty."
The U.S. government has struck mutual legal assistance treaties, or MLATs, with about a third of the world's countries. The mechanism, while useful, can clog the wheels of justice.
"It's a slow and laborious process. It often takes months, if not years, for governments to respond," said Jennifer Daskal, a former attorney in the National Security Division of the Justice Department who now teaches law at American University's Washington College of Law.
More criminal cases than ever involve digital evidence, she said, and "the volume (of MLAT requests) is just going to keep on increasing exponentially."
Something else likely to go unmentioned in the Supreme Court chambers is the name of Edward Snowden, the former National Security Agency contractor who spilled secrets about U.S. surveillance programs in 2013 before taking exile in Moscow. Snowden's acts have shaped views abroad of what some critics see as the extraterritorial reach of the U.S. government.
"In the wake of the Snowden revelations, levels of trust around the world in the American government went down," Woods said. "American businesses ever since have been scrambling to reassure customers around the world that they resist the American government."