Pharrell Williams has sent Donald Trump a legal challenge over his use of the song Happy on the day of the Pittsburgh synagogue massacre.
Lawyers for the singer issued Mr Trump a cease and desist letter after he played the song at a political event in Indiana "on the day of the mass murder of 11 human bring at the hands of a deranged 'nationalist'".
The president had played the song at the Future Farmers of America rally in Indiana just hours after the mass shooting killed 11 people – predominantly elderly Jewish Americans from a tight-knit community – as they worshipped on Saturday morning.
"There was nothing 'happy' about the tragedy inflicted upon our country on Saturday and no permission was granted for you use of this song for this purpose," the letter continued.
It warned that use of the song constituted a copyright infringement and Pharrell's trademark rights.
"Pharrell has not, and will not, grant you permission to publicly perform or otherwise broadcast or disseminate any of his music," the letter said.
At the rally, Trump described the shooting as an "evil anti-semitic attack" that was an "assault on all of us".
During his speech to the Future Farmers of America, Trump entered to the song “Happy;” joked about cancelling tonights rally because hes having a bad hair day; and used the anti-Semitic "globalist" dogwhistle hours after a mass shooting at a synagogue.pic.twitter.com/u8ANgnWzzE
— Shannon Watts (@shannonrwatts) 27 October 2018
But he also attracted criticism both for the choice of music and for making a joke about having a "bad hair day".
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This is not the first time Trump has received a cease and desist application over his use of music at a rally.
The estate of Prince warned him about playing the late star's song Purple Rain at rallies, while Aerosmith frontman Steve Tyler took action over the use of his song Livin' On the Edge.