Whistleblower

A whistleblower is someone in an organization who witnesses behavior by members that is either contrary to the mission of the organization, or threatening to the public interest, and who decides to speak out publicly about it.

It is not uncommon for whistleblowers to be all but quickly excluded from the organization. Official laws protecting whistleblowers exist in several countries.

See also: [suppression of dissent]?

Relevant links:

US Government Accountability Project: http://www.whistleblower.org
US National Whistleblower Project: http://www.whistleblowers.org