LOS ANGELES (CBSLA) — A trial starts Thursday to determine whether Katy Perry’s hit song “Dark Horse” lifted its underlying beat from a gospel rap song.

The lawsuit was filed in 2015 by Marcus Gray, whose raps under the name Flame, and claims Perry lifted portions of his 2012 gospel rap song “Joyful Noise” for her 2013 hit “Dark Horse.” The singer was spotted on her way into the federal courthouse Thursday morning.

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Perry, who is expected to testify at some point, was seen nodding her head to the beat of “Dark Horse” when it was played for jurors.

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Perry’s attorneys tried to get the lawsuit thrown out, claiming she did not know Gray and had never heard the song before. But a judge determined the lawsuit could go forward because it had been viewed millions of times on YouTube and Myspace and had been nominated for a Grammy.

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This is the latest case of musical copyright infringement involving a high-profile musician. In 2016, a jury decided Led Zeppelin did not steal the opening riff of the classic “Stairway to Heaven” from the Spirit song “Taurus.” A year earlier, a jury agreed with the family of Marvin Gaye that Robin Thicke’s hit song “Blurred Lines” infringed on the R&B legend’s song “Got to Give It Up” and awarded them millions.