Sir Paul McCartney has filed legal papers in the US, as part of an attempt to reclaim the publishing rights to The Beatles' back catalogue.
Although he co-wrote most of the band's hits, the star has never controlled the publishing.
However, the US copyright act of 1976 gives writers the opportunity to reclaim the rights after 56 years.
The Lennon-McCartney catalogue becomes available in 2018, and Sir Paul has recently moved to recapture it.
According to Billboard, the star filed a termination notice for 32 songs with the US Copyright Office in December.
Most of the songs date from 1962 - 1964, although others come from much later in the band's career. Some of those, including Come Together and Why Don't We Do It In The Road, are not due to become available until 2025.
An unnamed source told the magazine Sir Paul would only regain publishing rights for his half of the compositions, most of which he co-wrote with John Lennon. Furthermore, the act only applies to the US, so The Beatles' back catalogue would remain in the hands of Sony / ATV in the rest of the world.
Publishing rights determine how a song can be exploited - for example by licensing its use in a film or television programme. The publisher shares any resulting royalties with the songwriters, helping Sir Paul to amass a personal fortune of £730m.
But the lack of control over the songs has long been a thorn in the musician's side.
In the very early days of their career, The Beatles' manager, Brian Epstein, persuaded Lennon and McCartney to form a publishing company with music impresario Dick James - explaining it would be the smartest way for them to make money from their songs.
Within a few years, the band had become bigger than anyone expected and the publishing company - Northern Songs - was floated on the stock market.
Lennon and McCartney ended up with a 15% share, while James and his partner Charles Silver took 37.5% between them as the company's chairmen.
George Harrison and Ringo Starr were given just 0.8% - prompting the former to write the bitter Only A Northern Song, expressing his dissatisfaction at being considered a junior songwriter within the company.
In 1967, after Epstein's death, relations between the band and the chairmen soured - and James abruptly sold the publishing rights to ATV Music for £1.5m (£24.5m adjusted for inflation), without giving notice to The Beatles, robbing them of the chance to obtain the rights for themselves.
Almost 20 years later, Michael Jackson bought the ATV catalogue - which by that time also included songs by Little Richard, the Pointer Sisters, Pat Benatar and The Pretenders - for $41.5m (£28.8m), permanently souring his friendship with Sir Paul.
"I think it's dodgy to do things like that. To be someone's friend and then to buy the rug they're standing on," the Beatle was quoted as saying in J Randy Taraborrelli's biography of Jackson.
In 1995, Jackson sold half of his share in ATV Music to Sony. The Japanese company purchased the remainder of Jackson's stake earlier this month.
While Sir Paul's motion to terminate copyright is likely to be successful, Lennon's share in the Beatles' songs will not return to his estate. Yoko Ono sold the rights to his music to Sony/ATV Music in 2009, with those rights lasting the entire copyright's lifetime (70 years).