Pharrell Williams is not happy that President Donald Trump used one of his most joyful hit songs at a GOP rally the day of the Tree of Life massacre this past weekend.

The Hollywood Reporter writes that the producer-artist is suing the president after playing Pharrell's song "Happy" at a rally in the Midwest just hours following the tragic Tree of Life Congregation synagogue in Pittsburgh, Pennsylvania on Saturday (October 27).

Now, Pharrell's lawyer, Howard King, has issued Trump a cease and desist letter.

"On the day of the mass murder of 11 human beings at the hands of a deranged 'nationalist,' you played his song 'Happy' to a crowd at a political event in Indiana," King wrote in the letter obtained by The Hollywood Reporter. "There was nothing 'happy' about the tragedy inflicted upon our country on Saturday and no permission was granted for your use of this song for this purpose."

Pharrell's attorney continued that the musician has not and will not grant the president permission to use his music, claiming that Trump's use of "Happy" was both a copyright and trademark infringement.

On October 27, 11 people were shot dead with many more injured during a domestic terrorist attack at the Tree of Life Congregation in Squirrel Hill. The suspect, Robert Gregory Bowers, was arrested and reportedly charged with 29 federal crimes and more than 35 state crimes.

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