Loomis and the Lust's lead singer and songwriter Will Loomis is claiming 'Domino' contains "substantially similar compositional elements" to his own song 'Bright Red Chords', which was released in 2009.
His attorneys are also alleging that the 24-year-old pop singer and her co-writers "wilfully infringed" on their copyright, resulting in "significant ill-gotten commercial advantage from the sale of "millions of copies of their derivative work".
They are seeking a jury trial and $150,000 in damages.
"When I wrote this melody in my garage I never imagine it would be sung for the King and Queen of England," Will wrote on his Facebook.
Jessie J's representatives have not responded to their allegations yet.
Listening to the two together, the melodies are pretty close. Let us know what you think.