Federal prosecutors investigate Boeing's 737 MAX

A federal grand jury issued a subpoena on March 11 to at least one person involved in the development of Boeing's 737 MAX aircraft on behalf of the Justice Department, though it remains unclear if the action is related to government scrutiny of the FAA's approval of the plane's MCAS anti-stall safety system, the Wall Street Journal reports.

Why it matters: As the WSJ notes, "it is highly unusual for federal prosecutors to investigate details of regulatory approval of commercial aircraft designs, or to use a criminal probe to delve into dealings between the FAA" and the largest aircraft manufacturer in the U.S. as safety oversight lapses are usually treated as civil matters.

Go deeper: What we've learned from the Boeing 737 MAX crashes