Between all the Super Bowl football action yesterday, one commercial seemed to have caught a lot of people's attention: to promote its smallest SUV, Jeep showed images of it all over the country, then the world, to the tune of Woody Guthrie's "This Land Is Your Land."

One reason people are discussing it is because appearing in a commercial would seem to run against the late Guthrie's values. Would Guthrie have ever allowed the song to be licensed to Jeep, and for a Super Bowl commercial?

The answer is that nobody had to license it. Ten years ago, EFF set out to defend an online political parody set to "This Land Is Your Land," by arguing that it was a fair use. Instead, we discovered through the course of litigation the song actually entered the public domain in 1973, and today there are no restrictions on its use. That means that organizers that share Guthrie's politics—and yes, companies like Jeep—are equally free to use the song.1

Of course, even when his songs were restricted by copyright, Guthrie was famously permissive. Just look at his Copyright Warning from the 1940s:

This song is Copyrighted in U.S., under Seal of Copyright # 154085, for a period of 28 years, and anybody caught singin it without our permission, will be mighty good friends of ourn, cause we don’t give a dern. Publish it. Write it. Sing it. Swing to it. Yodel it. We wrote it, that’s all we wanted to do.

Given the duration of copyright terms and the control many artists and publishers try to exert, it can seem like any use is an endorsement. But Woody Guthrie preached the value of sharing freely—and when it came to his music he practiced it, too.

• 1. There are a few caveats here. For one, this recording of the song needs to be licensed. For another, our client settled its case after we made the public domain discovery. Even though we documented the timeline by which the song entered the public domain, it's possible that the publisher Ludlow Music still requests—and receives—licensing fees. Finally, there are a few variations of the composition, and some may still have copyright restrictions.