Federal law enforcement's growing reliance on foreign partners as U.S. prosecutors build cases against targets abroad will have to adjust to a new reality after the U.S. Court of Appeals for the Second Circuit curtailed compelled testimony use in cross-border prosecutions.

The same day the decision came down in United States v. Allen, 16-898-cr, acting assistant attorney general Kenneth Blanco, in remarks to the Atlantic Council Inter-American Dialogue, said the Department of Justice's “biggest investigations are increasingly transnational, often involving multiple foreign jurisdictions.”

“As transnational crime continues to grow in scope and complexity, we increasingly find ourselves looking across the globe to collect evidence and identify witnesses necessary to build cases, requiring greater and closer collaboration with our foreign counterparts,” Blanco said.