There are certain songs anyone in the world can sing along to. “Thriller” by Michael Jackson, “One Love” by Bob Marley, and of course, probably the world’s most-known song, “Happy Birthday.”

Sisters Patty Smith Hill and Mildred Hill are said to have rights to “The Birthday Song,” but after a recent judge ruling, this popular celebration song is potentially free from copyright. A federal judge ruled filmmakers challenging Warner/Chappell Music’s hold on the birthday tune should be granted summary judgment. The judge believes there are not enough facts to fully grant rights to anyone for the song.

So, what exactly is the history behind “The Birthday Song”? The song dates all the way back to the late 19th century and was written by the Hill sisters. The Hill sisters later gave rights to a publishing company owned by Clayton Summy. Eventually copyright registrations were made by Sumny’s company to own the rights to “The Birthday Song.” The main issue in this case is that the Hill sisters never objected to publication until 1934, which was four decades after they wrote the song. Even then, the Hill sisters proclaimed rights on the melody, not the lyrics. You can see how confusing this case can be, considering how long ago the song was written. For now, we’ll just continue to sing Happy Birthday and blow out our candles freely.