Catholicism has, over the course of American History, become a vital part of the American landscape. From the Catholic founding father Charles Carroll and his cousin Bishop John Carroll (an early supporter of a vernacular Mass) to President Kennedy, Catholicism made a claim to be a faith compatible with American ideals, and over a century and more it proved itself to be so.
A separation between Church and state came to be welcomed as it allowed Catholics to send their children to Catholic schools, rather than the de-facto protestant state-run schools found in places like Massachusetts. American Catholics embraced democracy and the democratic process, rather than opposing it like many in Europe, who viewed republicanism as inherently anti-clerical. American Catholic churches featured greater lay participation in their management as well.* The Catholic Hierarchy objected to a number of these views, characterizing the American church's tendencies as the heresy of "Americanism", and tried off and on to bring the American church more in line with Rome.**
Beyond the organizational and political controversies, American Catholics became more and more like other Americans and less and less like European Catholics on a number of other issues. In the 50's, 60's and 70's, contraception became accepted by the mass of American Catholics. This continues to this day - the vast majority of sexually active Catholic women use some sort of contraception, and Catholic opinions on most issues track those of the general populace quite closely (see here for examples).
When Vatican II came, it seemed like the American Catholic view of the faith would win out. Alas, it was not to be. The hierarchy fought back, restated it's rejection of contraception in Humanum Vitae, rejected further ecclesiastical reform (particularly regarding infallibility and the role of women) and condemned liberation theology.
Lately the most salient feature of the Hierarchy's reaction is the prominent role of the US council of bishops, led by Achbishop (now Cardinal) Timothy Dolan. They have generally presented themselves as speaking for Catholics generally, and the media have often gone along with this. When examined more closely, the claim that the Bishops speak for Catholics is an odd one -- most Catholics don't seem to agree with them on Birth Control or a host of other issues.
Why then do they speak for Catholics? The answer is simple -- because they are the instruments of the Church, the appointed authorities of the Catholic Hierarchy, ordained by the Pope and thus by God. They speak for Catholics because they say so. The right of Catholic Bishops to speak for Catholics is a religious claim based on the church's doctrine and autocratic organization, not on the actual opinions of American Catholics. It is a rebuke to the independence of the American Catholic conscience that evolved over the decades -- the Bishops, not the mass of the laity, are the only people whose opinion matters.
Thus if we concede Cardinal Dolan his right to speak for Catholics, we concede half the argument. Dolan's authority comes from one of the most authoritarian selection processes left on earth -- one that excludes women and non-ordained men from even having a voice. As believer in the American principle that only those selected by the people may speak for them, I cannot assume that Dolan speaks for anyone other than himself.
*See Howe's What Hath God Wrought for details on this.
**The road to American Catholic assimilation was rockier than they way I lay it out here in other ways as well -- Bishop John Hughes was an anti-protestant, racist, reactionary snake who opposed some of the worthiest causes of his time (such as abolition or its more moderate relatives, Free-Soil and the Republican Party of Lincoln). Cardinal Dolan wore John Hughes' cross when he was consecrated as Archbishop of New Yrok.