One on of the big problems we face is distinguishing it from other genres; especially other 'factual' genres such as news, sport, etc.
We can see that the hybrid forms of (broadcast) documentary give us some clues;
- Mockumentary (e.g. The Office, Spinal Tap, etc) shows that documentary is not comedy or satire because it has to cross with that other genre to produce this hydrid.
- Reality TV (or Banality TV - see Taylor PA, & Harris JL, Critical theories of mass media: then and now, Open University Press, 2007) (e.g. BigBrother, Survivor, Ship Wrecked, The Apprentice, etc) shows that documentary is not game show.
- Docu-Soap (e.g.The Osbournes, Driving School, Airport, etc) shows it is not soap-opera.
- Pseudo-Soap (e.g. The Hills) shows the popularity of docusoap as a form and the ease with which it can be bent to suit the needs of producers.
- Docufiction (e.g. City of God) shows that documentary is not not Cinéma Vérité (even if they are closely related). Andy Warhol’s Empire (1964) is 8 hours of slow motion footage of The Empire State building composed in massive takes without editing and is clearly not documentary.
- Docudrama (e.g. United 93, The Battle of Algiers, Bloody Sunday, Battle for Haditha, Hillsborough) shows that documentary is not drama.
Things are less clear in other media, i.e ‘e-media’ & print, because most of what we might consider to be ‘documentary’ can be subsumed into journalism, photography, or other fields. The two main areas of documentary action in these media are photo-journalism & reportage and both are hybrids with journalism.
Photo-Journalism - It is hard to be certain what counts as photo-journalism and what is photography more broadly. The work of Weegee, Robert Capa, Henri Cartier-Bresson, Don McCullin et al was documentary but Ansel Adams, Atget, and all other photographers also documented. A very delicate modality judgement about what is to be included and what excluded is necessary and it is not always clear whether the photographic is documentary (consider the problematic nature of google street view).
Reportage - In many ways reportage is even more loosely governed and problematic than photo-journalism. The works of Ryszard Kapuściński seem emblematic of the form but Hunter S Thompson’s far more complex and literary works would also fit into this generic category (even Fear & Loathing in Las Vegas could be seen as reportage). Again it is a question of modality and judgement.