By Patrick Gavin for Politico.

Robert Greenwald, the filmmaker behind such documentaries as “Outfoxed,” “Wal-Mart: The High Cost of Low Price” and “Koch Brothers Exposed,” has turned his lens on the subject of drones in “Unmanned: America’s Drone Wars,” and he’s bringing his message to the Hill.

Greenwald will play a clip from the film Tuesday at a briefing called by Rep. Alan Grayson (D-Fla.) at the Rayburn House Office Building. The film features interviews with such politicos as retired Army Colonel Lawrence Wilkerson, former chief of State to Secretary of State Colin Powell and former advisor to NATO David Kilcullen.

“I don’t think we should be killing people without evidence, judge, jury and trial — some aspects of that,” Greenwald told POLITICO. “There must be investigations because many innocent people have been killed. … And there has to be transparency. Think about it for a minute: People are being killed and there absolutely no checks and balances of any conceivable kind. And I think if another country were doing this, we’d be outraged.”

To hammer his point home, Greenwald is also bringing to victims of American drones with him to Tuesday’s briefing: Rafiq ur Rehman, who lost his mother to a drone strike and his two children who were injured by a drone strike.

“The more people know about it, the more they will be outraged by it,” said Greenwald, who says that many congresspersons he’s spoken with have “a lack of awareness of what is going on, the number and variety of innocent people being killed.”