The film's screenplay beat out those of Bridge of Spies, Ex Machina, Inside Out, and Straight Outta Compton.
"We made this film for all the journalists who have and continue to hold the powerful accountable, and for the survivors whose courage and will to overcome is really an inspiration to all," said Tom McCarthy, alongside co-writer Josh Singer. "We have to make sure this never happens again."
Emily Blunt and Charlize Theron presented the first award of the night. The order of awards was changed to illustrate the filmmaking process itself.
The awards are being handed out at the Dolby Theatre in Hollywood. Chris Rock is hosting.
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