WASHINGTON (AP) — Attorney General Merrick Garland directed U.S. attorneys across the country to swiftly prioritize prosecution of federal crimes that happen on commercial flights as federal officials face a historic number of investigations into passenger behavior.

Garland's memo, issued Wednesday, emphasizes that the Justice Department is committed to aggressively prosecuting violent passengers who assault crew members or endanger the safety of other passengers. Federal law prohibits interfering with a flight crew, including assaulting, intimidating or threatening crew members.

In a statemen...