The question ‘Who was the Walrus?’ has been discussed in some detail ever since 1967, when John Lennon famously declared (in song form) “I am the Walrus” *see note below.
The legal implications of whether he was (or was not) the Walrus have received less attention though, prompting attorney Ezra D. Landes to write a paper on the subject for Pepperdine Law Review, Volume 34, in which he points out that, just one year on in 1968 (Glass Onion), Lennon strongly suggested that the Walrus was in fact Paul (McCartney).
To complicate matters further, in a later interview with David Sheff, Lennon changed tack again and hinted that yes, he indeed was the Walrus, and that the ‘Glass Onion’ lyric was just a way of getting in a sly dig at McCartney.
The legal ramifications of all this are explained in : ‘I Am the Walrus – No, I Am!: Can Paul McCartney Transpose the Ubiquitous ‘Lennon/McCartney’ Songwriting Credit to Read ‘McCartney/Lennon?’ An Exploration of the Surviving Beatle’s Attempt to Re-Write Music Lore, as it Pertains to the Bundle of Intellectual Property Rights.’
*Note: In the same song Lennon also claimed “I am the Egg Man”, the legal implications of which have as yet been underexplored in the literature.