American Airlines has subpoenaed both Google and video-sharing site YouTube, demanding that they reveal the identity of the person who posted part of a flight attendant training video on their sites.
American Airlines says the video is copyrighted and has subpoenaed the companies using the US Digital Millennium Copyright Act.
Under the act, companies have the right to request information when copyright on their materials is allegedly infringed.
The video at the centre of the airline’s action is called "Flight Attendant, Upside Down".
Both Google and YouTube have requested that American Airlines put its request through a court. Both are now investigating the posting to their sites.
Both companies say they comply with US state and federal laws, and YouTube warns users that copyrighted materials can only be posted by copyright holders.