There are few economic issues on which the Church's teaching is more clear than the importance of organized labor within a market economy. Here, for example, is John Paul II in Laborem Exercens:
All these rights, together with the need for the workers themselves tosecure them, give rise to yet another right: the right of association, thatis to form associations for the purpose of defending the vital interests ofthose employed in the various professions. These associations are called labouror trade unions. The vital interests of the workers are to a certain extentcommon for all of them; at the same time however each type of work, eachprofession, has its own specific character which should find a particularreflection in these organizations.
. . . . [M]odern unions grew up from the struggle of theworkers-workers in general but especially the industrial workers-to protecttheir just rights vis-a-vis the entrepreneurs and the owners of themeans of production. Their task is to defend the existential interests ofworkers in all sectors in which their rights are concerned. The experience ofhistory teaches that organizations of this type are an indispensable elementof social life, especially in modern industrialized societies. . . . It is always to be hoped that,thanks to the work of their unions, workers will not only have more, butabove all be more: in other words, that they will realize their humanitymore fully in every respect.
Building on John Paul's discussion, the US Bishops said the following in Economic Justice for All:
104. The Church fully supports the right of workersto form unions or other associations to secure their rights to fairwages and working conditions. This is a specific application of themore general right to associate. In the words of Pope John Paul II,"The experience of history teaches that organizations of this type arean indispensable element of social life, especially in modernindustrial societies" [58]. Unions may also legitimately resort tostrikes where this is the only available means to the justice owed toworkers [59]. No one may deny the right to organize without attackinghuman dignity itself. Therefore, we firmly oppose organized efforts,such as those regrettably now seen in this country, to break existingunions and prevent workers from organizing. Migrant agriculturalworkers today are particularly in need of the protection, including theright to organize and bargain collectively. U.S. labor law reform isneeded to meet these problems as well as to provide more timely andeffective remedies for unfair labor practices.
In fact, in many cases in which the magisterium talks about leaving questions of economic justice to be resolved in the private sphere, according to the principle of subsidiarity, it has in mind not an unregulated market, but rather the resolution of those issues through negotiations between employee unions and employers. For example, in Centesimus Annus, John Paul said:
[S]ociety and the State must ensure wage levels adequate for the maintenance of the worker and his family, including a certain amount for savings. This requires a continuous effort to improve workers' training and capability so that their work will be more skilled and productive, as well as careful controls and adequate legislative measures to block shameful forms of exploitation, especially to the disadvantage of the most vulnerable workers, of immigrants and of those on the margins of society. The role of trade unions in negotiating minimum salaries and working conditions is decisive in this area.
In other words, unions are a key part of the Church's conception of the sorts of mediating institutions that take some of the pressure off the state to attempt to fully implement economic justice through legal interventions in the market. And so it is worth more than a passing notice that the Democrats are trying to do something that will (hopefully) help reverse the decades-long decline in private sector unionization:
The legislation, also called the card check bill, would certify aunion as soon as a majority of workers at a plant signed cardsauthorizing it. Currently, employers can require elections, overseen bythe National Labor Relations Board, on whether a union should be recognized.
Thelabor rights group American Rights at Work said that, in the run-up tosuch elections, 80 percent of employers hire union-busting consultantsand 90 percent force employees to attend one-on-one anti-union meetingswith their supervisors.
The legislation would toughen penaltiesagainst employers who violate worker rights during organizing drivesand set up a binding arbitration process to prevent companies fromthwarting a new union by bargaining in bad faith on an initial contract.
Perhaps unsuprisingly, the White House has threatened to veto. In opposition to the bill, Republicans are raising arguments about protecting workers' rights not to unionize and relying on a rhetoric that demonizes labor unions ("union bosses," etc.) in a way that is fundamentally at odds with the Catholic attitude towards these organizations:
The celebrations may be short-lived. Senate Republican leader Mitch McConnell, R-Ky., has pledged to block the bill and the White House says President Bush will veto the measure if it reaches his desk.
The House vote was short of the two-thirds majority that would be needed to overturn a veto. Thirteen Republicans voted for the measure; two Democrats voted against it.
...Boehner said the bill really was about ''taking care of union bosses. ... This is an effort to help them get more members, to make it easier for them to sign them up and to intimidate them to sign cards.''
The case for the charge that card elections open the door to union intimidiation is less than robust. First, there is data that suggests that employers are far more likely to attempt to coerce workers during a protracted election campaign than unions are during card-check elections. Via American Prospect (HT Kevin Drum):
A poll commissioned by American Rights at Work (a pro-union org),Rutgers University, and Jesuit Wheeling University surveyed 430randomly-selected workers from worksites where employees had soughtunions either through the NLRB election process or card-check. Thesurvey included workers who voted both for and against the union, andincluded campaigns in which the unions both won and lost. The EagletonResearch Center and Rutgers conducted the calls over a couple of weeksin 2005.
The results were telling: 22% of workers surveyed said management"coerced them a great deal.' 6% said the same for unions. During theNLRB election, 46% of workers complained of management pressure. Duringcard check elections, 14% complained of union pressure. Workers in NLRBelections were twice as likely as workers in card check elections toreport that management coerced them to oppose (it's worth noting thatin card-check elections, 23% of workers complained of managementcoercion -- more than complained of union coercion). Workers in NLRBelections were more than 53% as likely to report that managementthreatened to eliminate their jobs.
In addition, the leverage that an unestablished union has over potential members is not nearly as great as that exercised by employers, who can, after all, fire their employees, depriving them of their livelihood.
UPDATE: I've updated the original post to add some more references to the documents of Catholic Social Teaching re. unions. and the data regarding coercion.