A US jury on Wednesday ruled that actor Amber Heard defamed ex-husband Johnny Depp in a widely watched six-week trial that featured explicit and graphic evidence and testimony detailing the former Hollywood couple's soured relationship.

The Virginia jury also ruled in favour of Heard in some aspects of her counter-suit against Depp.

The jury awarded Depp $15 million in damages from Heard. The panel awarded Heard $2 million in damages.

Depp, the 58-year-old Pirates of the Caribbean star, sued Heard for $50 million and argued that she defamed him when she called herself "a public figure representing domestic abuse" in a newspaper opinion piece.

Heard, 36, countersued for $100 million, saying Depp smeared her when his lawyer called her accusations a "hoax".

Depp has denied hitting Heard or any woman and said she was the one who turned violent in their relationship.

Depp and Heard met in 2011 while filming The Rum Diary and wed in February 2015. Their divorce was finalised about two years later.

At the centre of the legal case is a December 2018 opinion piece by Heard in the Washington Post in which she made the statement about domestic abuse. The article did not mention Depp by name but his lawyer told jurors it was clear that Heard was referring to him.

During six weeks of testimony, Heard's attorneys argued that she had told the truth and that her comments were covered as free speech under the US Constitution's First Amendment.

Throughout the case, jurors listened to recordings of the couple's fights and saw graphic photos of Depp's bloody finger. He said the top of the finger was severed when Heard threw a vodka bottle at him in 2015.

Heard denied injuring Depp's finger and said Depp sexually assaulted her that night with a liquor bottle. She said she struck him only to defend herself or her sister.

Testimony was livestreamed widely on social media, drawing large audiences to hear details about the couple's troubled relationship.

Once among Hollywood's biggest stars, Depp said Heard's allegations cost him "everything". A new Pirates movie was put on hold and Depp was replaced in the Fantastic Beasts film franchise, a Harry Potter spinoff.

Depp lost a libel case less than two years ago against the Sun, a British tabloid that labeled him a "wife beater". A London High Court judge ruled that he had repeatedly assaulted Heard.

Depp's lawyers filed the US case in Fairfax County, Virginia, because the Washington Post is printed there. The newspaper is not a defendant.