Western music is made up of just 12 notes, which yield a practically infinite number of songs. That's the theory, at least. It's only natural that composers mimic what's been successful in the past, but as Robin Thicke and Pharrell learned the hard way, there's a blurred line between inspiration and theft. And musical copyright continues to be a hot-button issue, affecting everyone from Madonna, Justin Bieber, Ed Sheeran and Lana Del Rey to the mighty Led Zeppelin.
Read on for 12 of the most infamous copyright infringement cases in pop music history. From lyrical lifts and unlicensed sampling, to melodies that sound just a tad too similar, there are many points of contention. Are the original artists looking out for their intellectual property or their bank balance? The jury is out.