FYI: It isn't inherently illegal (at least federally). Just like using other aerial vehicles, you have to get FAA authorization, and in some cases an exemption.
1) News media require FAA authorization for news gathering with a drone.
2) Hobby drone pilots require FAA authorization if they intent to capture news and sell them to the news media.
3) Hobby drone pilots do not require FAA authorization if they have no intent of news gathering but happen to come across news and then give the resulting video or images to the media.
4) News media do not require FAA authorization if they acquire news captured by an unaffiliated third-party drone pilot.
The devil is in the details, so I would recommend studying carefully the two-page legal opinion from the
FAA’s Assistant Chief Counsel for Regulations dated May 5, 2015, entitled Media Use of UAS, and apply your own analysis to your specific circumstances and plans.