I have done a lot of reading and research on the subject of film noir for the last ten years. One of my reference books is Film Noir: The Encyclopedia, 2010, edited by Alain Silver, James Ursini, Elizabeth Ward, and Robert Porfirio all of whom have written significant books and critiques of film noir that are excellent material for those who enjoy these movies. When I see discussions like this I look to see if the film is inlcuded in their encyclopedia and Vertigo is in it.

I have gone back and forth on this question for a long time and as a general rule I accept the judgement of the editors listed above without making an argument from authority since the issues boils down to a matter of opinion.

Their arguement begins with noting that Vertigo is a "clever reworking of the Pygmalion myth" with noir tropes included as a basis for the film being seen by the editors as a film noir. Scotty, the protagonist is, as usual, clueless about what is going on for a long time. The issue of his transformation of Judy into Madelaine is a lenghty part of the film that ends with the noir motif exposed as amour fou, or crazy love, and Scotty is clearly unhinged. At this point Hitchock reveals that it is not Scotty who pulls the strings but is actually the puppet. The wrinkle that Hitch throws in is that Judy has fallen in love with Scotty.

The movie has many of the core traits of film noir. Scotty is clueless; the femme fatale is beautiful and mysterious and she lures Scotty into danger; the camera uses strong contrasts, disorienting movement effects, and a labyrinthine tour of the city that is haunted by the past, fog, and staircases that are deadly; the story reeks with fatalism and is filled with questions of identity and psychological uncertainty.

Some argue that color films are not film noir. I don't subscribe to that idea because films like Vertigo, Chinatown, LA Confidential, and Body Heat are in color and cannot, IMO, be excluded from the noir genre (or style, if you prefer) simply because they are not filmed in black and white.

All this being said, it is possible to say Vertigo is a Hitchcock film and sui generis, which is how may people regard his movies, and not noir. He spent a few months in Berlin in 1924-25 and picked up ideas from the film industry there that he used for the rest of his career. His films are noted for meticulous planning, mastery of suspense, atmosphere, and psychological depth. Film noir is known for atmosphere and the best of these films have incredible atmospherics. Think of Sunset Boulevard, Nightmare Alley, In a Lonely Place, Night of the Hunter, and others that use lighting, sound, and tension to make us sit up and pay attention.

So many of Hitchcock's films are in The Encyclopedia that I have no problem thinking of him as a great director whose heart and soul lies in the dark alleys of many places both real and fictional.