In these situations, the alleged source song was a popular one — the case could be made that even if there was no direct influence, there was an ambient one. Copyright law makes no distinction between conscious and unconscious copying, which means that even though fully unpacking claims like these might mean parsing the difference between outright and unconscious theft, or between thievery and parallel influence, those distinctions may well be, apart from the determination of damages, moot.

Cases like that are the exception, though. Most of the allegations that have been brought in recent years stretch the bounds of credulity.

A singer-songwriter named Steve Ronsen suggested that a passage in “Shallow,” the Lady Gaga/Bradley Cooper hit from “A Star Is Born,” is partly derived from one of his songs, “Almost,” and threatened a lawsuit. The Weeknd was sued by a trio of songwriters — Brian Clover, Scott McCulloch, and William Smith — who allege that his song “A Lonely Night” was a rip-off of an unreleased song called “I Need Love” that they’d written more than a decade earlier. Migos were sued by a rapper, M.O.S., who said that the title phrase of their song “Walk It Like I Talk It” had appeared in a song of his more than a decade prior (the case was dismissed). Miley Cyrus is being sued by a Jamaican performer, Flourgon, over a lyric in her song “We Can’t Stop.” Ed Sheeran has been the target of several lawsuits; an infringement claim for an ostensible borrowing on “Shape of You” from a singer named Sam Chokri has his royalty payments for that song on hold. But in almost all of these cases, the scope of the alleged infringement is so minor, so generic, that it suggests that a basic element of composition is up for an ownership grab.