Copyright doesn't last forever, or at least it's not meant to; by the letter of the law, it runs through the life of the creator plus some length of time thereafter, ranging up to 120 years depending on the nature of the work and the period of time it was created, as well as whether it was previously protected under existing copyright law at the time. If you're looking for an informative, of somewhat confusing, read, you can check out the full document on copyright duration provided by the U. S. Copyright Office.
Notable within those rules is one section concerning copyright duration under the 1909 Act, which specifies that copyright existed on a work for 28 years after its publication, and another 28 years after that if the copyright were to be renewed. It's under these rules that Woody Guthrie wrote and published his iconic song "This Land is Your Land", and these same rules that opened the door for a lawsuit against the song's copyright holders, albeit one that failed to convince a federal judge.
Judge P. Kevin Castel dismissed a lawsuit brought by the band Satorii against the Richmond Organization and Ludlow Music, in which the band asserted that the Guthrie song belongs in the public domain, as the copyright had not been renewed in 1973 — 28 years after its initial publication. In dismissing the case, Judge Castel noted that Satorii had already paid the licensing fee for use of the song, and thus there existed no legal dispute to adjudicate, although the suit had asked the publisher to return licensing fees paid since 2010 to the artists. Satorii and its lawyers attempted to build a case from old paperwork and songbooks owned by Guthrie to argue that the songwriter had renounced any claims to ownership, but the fact that the band had already paid the licensing fee (amounting to $45.50) negated any case they had built.
The case, while fairly straightforward in its dismissal, is that much more interesting for the politics of the song itself and its singer. While the song has become a staple of the patriotic songbook, Guthrie himself was given towards socialism and at least adjacent to the American Communist Party, and the original version hewed a bit closer to those politics than the version that children (myself included) grew up singing in school. And while holding onto the rights might seem antithetical to what one would presume Guthrie would want, given those leanings, his daughter Nora, who runs Woody Guthrie Publications, insists that maintaining the copyright is about preventing the song from being misused by those who would misrepresent its message.
Politics aside, it's another example of a popular song potentially hitting the public domain, like "Happy Birthday" before it. One wonders that as more profitable songs approach the date of their copyright expiration, whether the rules will change to ensure the payday doesn't.