Rule 15 B
An original song consists of words and music, both of which are original and written specifically for the motion picture. There must be a clearly audible, intelligible, substantive rendition (not necessarily visually presented) of both lyric and melody, used in the body of the motion picture or as the first music cue in the end credits.
In the 1960's with the demise of the original movie musical many
nominated songs were title songs like "Born Free", "Days of Wine
and Roses", "Never on Sunday". Starting in the 70's a song was
often just thrown in hoping for a nomination; "The Morning After",
"We May Never Love Like This Again", "It's Easy to Say". Without
looking them up can you name the movies? Exactly. The songs have
nothing to do with the movie.
I find it interesting that the first song from a James Bond movie
nominated was in 1977. None of the iconic 60's opening credits
songs were even nominated. The exception (kind of) is the non
Bond Bond movie "Casino Royal" in '67.
Another thing that I don't quite understand is that during the telecast
the nominees for Best Picture are given a 60 second clip but the
nominees for Best Song are done in their entirety - usually 4 to 5
minutes.