There’s an adage, of murky provenance, that music executives like to cite whenever another copyright infringement lawsuit lands: “Where there’s a hit, there’s a writ.”

The trial over Ed Sheeran’s Grammy-winning song “Thinking Out Loud” (2014), which began on Monday in Federal District Court in Manhattan, is the latest in a long line of music copyright suits. In the United States, it goes back to at least 1844, when a New York judge heard a case about the unauthorized reproduction of a song called “The Cot Beneath the Hill.” The plaintiff was awarded $625 in damages, according to a historical database maintained by the legal scholar Charles Cronin.

For Sheeran, the stakes are much higher. He is accused of copying passages from Marvin Gaye’s “Let’s Get It On” (1973); the family of Ed Townsend, Gaye’s co-writer, filed the suit in 2017. If Sheeran is found liable, a jury will set damages, which would likely be in the millions.

Here is a guide to some of the most consequential music copyright cases in recent decades, along with excerpts from their recordings.

But remember: It can be tricky, and even misleading, to compare recordings alone. In cases like these, the only material in question are the songs’ underlying compositions: the melodies, chords and lyrics that can be notated on paper. Elements specific to the performance captured in a particular recording — like the tempo, or the timbre of an instrument — are irrelevant.

Juries must decide not only if one song copies another, but whether the earlier song was original and distinctive enough to be protected by copyright.

“The problem with cases like this is that people ask the wrong question,” said Joe Bennett, a professor at the Berklee College of Music who works as a forensic musicologist in legal cases. “They ask the question, ‘How similar is song B to song A,’ whereas what they should be asking is how original is song A.”

Got that? In that case, put your headphones on and judge for yourself.

Bright Tunes Music v. Harrisongs Music (1976)