"Like Arresting the Holy Father"

There was mass picketing every Saturday afternoon during the Ohrbach strike, and every Saturday the police drove up with patrol wagons and loaded the pickets into them with their banners and took them to jail.  When we entered the dispute with our slogans drawn from the writings of the Popes regarding the condition of labor, the police around Union Square were taken aback and did not know what to do.  It was as though they were arresting the Holy Father himself, one of them said, were they to load our pickets and their signs into their patrol wagons.--Dorothy Day, The Long Loneliness, pg. 206.

At the time she was writing this, the great social encyclicals were Rerum Novarum and Quadregesimo Anno, though that certainly does not exhaust all the papal writings on labor before the publication of The Long Loneliness.