Another singer, Helen Kane, saw Jones' act in 1928, and first took on her style in her song "That's My Weakness Now". Kane then used Jone's catchphrase while performing in the Broadway musical Good Boy, becoming famous overnight for her own version of "I Wanna Be Loved By You."
In 1930, Max Fleischer introduced his Betty Boop character on Paramount's Talkatoon series, as an anthropomorphic French poodle. Boop became human in 1932, her floppy ears being exchanged for hoop earrings. Kane's imitation of Jones' singing style became the inspiration for the voice of Betty Boop. Kane attempted to sue Fleischer Studios for "using her persona", with the studio arguing that Kane had in fact used someone else's persona too; that of Esther Jones.
An early recording of Baby Esther's performance was used as evidence (Jones' was presumed to have died at this point), with Jones' manager testifying to the fact that Kane had been to see Jones' act in 1928.
After a two year trial, Kane's theft was exposed, and the court ruled that Kane did not create the "baby" style of singing, or the phrase "boop-oop-a-doop", with that credit going to Jones. The Judge also ruled that Boop's appearance more closely resembled that of actress Clara Bow.
While visually, Max Fleischer clearly took inspiration for Betty Boop from Helen Kane, Esther Jones influence on that character is undeniable; Kane's style simply wouldn't have existed had she not seen Jones' performance to copy it from. America has a long history of appropriating black artists and erasing them from history, and it's a shame Jones' died without knowing about this trial or ever receiving credit for the role she unknowingly played in Betty Boop's creation (although she is often referred to as Boop's "black grandmother" by those who know of her).