The State Governor of Wisconsin had used the song as entrance music at an event at which he appeared. This is very similar to the fashion in which entrance music used by professional wrestlers. The band has yet to send a formal cease and desist warning to Walker, but it seems like they got their message across pretty well.
If you're interested in more instances in which music was used by politicians without permission from the artists, Rolling Stone compiled a neat little list at this link:
If you think of anymore instances like this, share 'em in the comments!