Sheldon Cooper’s ultimate favorite lullaby is facing legal threats. CBS Network is accused of stealing the lyrics to the song, ‘Soft Kitty’. The lyrics, which was popularized by the sitcom throughout its nine-year run, according to reports was originally published by a New Hampshire teacher named Edith Newlin.

USA Today has learned that the heirs of Edith Newlin are suing the network and other parties associated with hit comedy. They have filed a copyright case against the network, claiming that Big Bang has been violating the song’s copyrights for years.

The plaintiffs, Ellen Newlin Chase and Margaret Chase Perry, claim that the lyrics of Song Kitty is similar to the 1930s version written by Edith Newlin without paying for the rights.

Newlin, a teacher, published the book called “Songs for the Nursery School” in which the words to Soft Kitty were part of. Fans of the hit comedy first heard the now controversial lullaby in an episode which aired in 2008.

According to NY Times, Edith Newlin passed away in 2004. Born in Indiana, she worked as a nursery teacher for over 30 years in Alstead, N.H. One of her daughters discovered the Big Bang Theory’s use of the lyrics in 2014 while doing a research about her mother’s life.

BBC reported that the suit also claims that the lyrics have also been used in selling multiple merchandises including: shirts, mouse pads, wallets, toys and fridge magnets among others.

"The Soft Kitty lyrics are among the best-known and most popular aspects of `The Big Bang Theory," reads a statement from the claim.
"They have become a signature and emblematic feature of the show and a central part of the show's promotion."

CBS, nor the showrunners and actors of The Big Bang Theory, have not yet commented on this ongoing legal matter. This is the first time the sitcom has faced a lawsuit throughout its nine seasons on air.