Johnny Depp's $50 million defamation suit against his ex-wife, Amber Heard, the actor's lawyers have issued subpoenas for Elon Musk, who Heard dated after she and Depp split, and the American Civil Liberties Union (ACLU), which Heard named as a recipient of half of her $7 million divorce settlement from Depp.Depp's team wants the ACLU to give testimony at a deposition and turn over all communications its had with Heard about donations, the defamation suit and the star's relationship with Depp,