Pope Pius XI
Quadragesimo Anno §85
Quadragesimo Anno: On Reconstruction of the Social Order
85 It is easily deduced from what has been said that the interests common to the whole Industry or Profession should hold first place in these guilds. The most important among these interests is to promote the cooperation in the highest degree of each industry and profession for the sake of the common good of the country. Concerning matters, however, in which particular points, involving advantage or detriment to employers or workers, may require special care and protection, the two parties, when these cases arise, can deliberate separately or as the situation requires reach a decision separately.
Source: Quadragesimo Anno (Vatican.va)