A song that became the "unofficial anthem to the civil rights movement" was wrongly placed under copyright, and should be released into the public domain. That's the argument in a lawsuit filed today in federal court over the song "We Shall Overcome."

Who's behind it? The same group of lawyers who fought for years to free "Happy Birthday" from copyright prison.

The 'Happy Birthday' case succeeded at last just a few months ago, and made it safe for little kids all over the world to sing the song over candlelit cakes at birthday parties, without fear of attorneys knocking on the door demanding royalty payments.

The new copyright battle is a proposed class action lawsuit that asks for copyright licensing fees to be returned. The case argues that royalties were wrongfully collected by Ludlow Music Inc. and The Richmond Organization, which claimed copyright over "We Shall Overcome" in 1960. But the song is probably based on an old African-American spiritual, according to popular belief–and the lawsuit.

The song is based on "an African-American spiritual with exactly the same melody and nearly identical lyrics from the late 19th or early 20th century," reads the complaint.

"This was never copyrightable to begin with," Mark Rifkin, an attorney for the plaintiff, told Reuters Tuesday. "The song had been in the public domain for many, many years before anyone tried to copyright it."

From Reuters:

The We Shall Overcome Foundation, the plaintiff, is seeking to produce a documentary film about song and its relationship to the civil rights movement. The group asked for permission to use the music in the film but was turned down by TRO, according to the lawsuit.

Ars Technica has a copy of the complaint here [PDF]. From Ars Technica:

At most, they say, the defendant companies own specific arrangements of the song, or additional verses that were added in 1960 when the song was copyrighted and again in 1963. Once more, the lawyers' chief client is a documentary filmmaker making a movie about the song in question. The named plaintiff is the We Shall Overcome Foundation, an organization created by the filmmakers. The foundation intends to make a movie about the song, and include a performance of it in "at least one scene in the movie."

From Ben Sisario's New York Times piece: