This novel was recommended to our Labour Relations class decades ago by the professor. Our professor was not on the left. In fact, he was a corporate lawyer and former downsizing hatchetman. (He got tired of firing productive workers, and became a professor.) He recommended the book because he felt it was important in any negotiation to understand the perspective of his opponents, and this novel provided that perspective for him.
In response to a comment below, "In Dubious Battle" is definitely NOT one of Steinbeck's well-known novels. It is traditionally rather obscure and hard to find, probably because of its politics. James Franco's recent film production has brought it some overdue attention.