Robin Thicke, Pharrell Williams Deny 'Blurred Lines' Copyright Infringement Claim

Artists deny that they ripped off a Marvin Gaye hit.

In court Wednesday, Thicke gave an impromptu concert, taking to a keyboard to perform a medley of famous songs to show how pop tunes often share similar chord progressions.

Other artists acknowledge that musical mimicry is sometimes practiced in the industry.

Thicke and Williams insist they are not copycats, calling any similarities between the two songs coincidental.

Because Gaye's song came one year before copyright laws were changed in the 1970s, jurors will not be able to hear the two songs side by side. Instead a stripped-down version of Gaye's song will be played.