Thania Garcia Some of the most high-profile copyright infringement cases happen in the music industry, where the accusation of plagiarism is as nebulous as a concept can get. It happens sometimes by accident — an “unconscious borrowing” — and other times it’s on purpose, deemed a “musical homage.” Ed Sheeran has been at the center of the latest most-talked-about case brought by the heirs of Ed Townsend, who co-wrote “Let’s Get It On” with Marvin Gaye. Sheeran made his first court appearance earlier this week to deny the claims that his 2014 song “Thinking Out Loud” lifts key elements of Gaye’s 1973 classic.