Late Monday afternoon, U.S. District Court Judge Susan Richard Nelson issued a ruling that may significantly alter professional football as we know it.

For six weeks, there has been a work stoppage in the National Football League as the league has sought to negotiate a new collective-bargaining agreement with the players. But Judge Nelson ordered the end of the stoppage and recognized the players' right to dissolve their union. By blessing this negotiating tactic, the decision may endanger one of the most popular and successful...