Taylor Swift has appealed against a decision to allow a trial over claims she stole lyrics used in her song Shake It Off.

The US singer's lawyers called the decision "unprecedented" and asked that the ruling by a California judge is looked at again.

Songwriters Sean Hall and Nate Butler allege Swift's lyrics were stolen from their 2014 song Playas Gon' Play, performed by girl group 3LW.

The song includes the lyrics "players, they gonna play, and haters, they gonna hate".

In Shake It Off, Swift sings: "The players gonna play, play, play, play, play, and the haters gonna hate, hate, hate, hate, hate."

According to court filings obtained by Billboard, Swift's lawyers say allowing a trial means the claimants could sue "everyone who writes, sings, or publicly says 'players gonna play' and 'haters gonna hate'."

"To permit that is unprecedented and cheats the public domain," they add.

Swift's lawyers say both songs use versions of "players gonna play" and "haters gonna hate" - but that both phrases are in the public domain and "free for everyone to use".

"The presence of versions of the two short public domain statements and two other tautologies in both songs... simply does not satisfy the extrinsic test," they say.

Swift's lawyers added: "Defendants respectfully request that the court revisit its ruling and apply the extrinsic test to the claimed substantial similarity in lyrics."

The extrinsic test requires the claimant proves substantial similarity after an objective comparison of specific elements within the songs.

The filings were made on Thursday at a court in the Central District of California.

The case has been dragging on for years.

In 2017, Swift's representatives called the songwriters' claim "ridiculous" and "nothing more than a money grab".

It was thrown out in 2018 but the pair appealed and the case was revived.