This was an election for the Wisconsin (state) Supreme Court, not the US (federal) Supreme Court. US Supreme Court justices are not elected; they are appointed by the President, as noted in your comment.
I get the chance to see it in person pretty often as well. It's definitely the coolest sculpture in the park. And the only one I've seen randomly show up around the Internet.
This was an election for the Wisconsin (state) Supreme Court, not the US (federal) Supreme Court. US Supreme Court justices are not elected; they are appointed by the President, as noted in your comment.