But as Burke's critics frequently note, plenty of Catholic bishops parrot this teaching without provoking such ire. They don't make headlines. They don't take on popular politicians or sports figures. And they certainly don't dwell on that sticky church law that forbids Catholics from receiving Communion if they obstinately persist in serious sin.

To do so would be public relations suicide. Every bishop knows it.

Yet Burke and a handful of his peers - including Archbishop Charles Chaput of Denver and Bishop Thomas Olmsted of Phoenix, among others - not only proclaim Catholic doctrine but also apply it to Catholics in their midst. Concerned that decades of cultural accommodation have left American Catholics indifferent to the 1.3 million unborn children aborted each year, these bishops prefer the mortification of a media circus to the queasy calm of ignoring injustice.

Their critics say they are unreasonable and out of touch. But history may say otherwise.

Not so long ago, U.S. Catholic bishops saw another group of people treated as disposable property. Although a paper trail of papal decrees condemning the slave trade stretches back to the early 1400s, most American Catholic bishops sat out the pre-Civil War abolition debate. Historians say they feared proclaiming the fullness of Catholic teaching on the subject, lest they jeopardize their precarious position in America and anger Catholics who supported slavery.

In a famous 1984 speech defending abortion rights, Mario Cuomo, a Catholic and a former governor of New York, described the bishops' refusal to back abolition as "a practical political judgment" with parallels to the personally-opposed-but-publicly-supportive position of pro-choice Catholics. Bishops who kept mum on a polarizing dispute they probably could not win "weren't hypocrites;" Cuomo said, "they were realists."

Cuomo's call to "realism" on abortion failed to win many converts among pro-life Catholics, who regard the timidity of 19th-century bishops on slavery as a cautionary tale, not an inspiration. Instead, pro-life Catholics find inspiration for their position in Archbishop Joseph Rummel of New Orleans and Cardinal Joseph Ritter of St. Louis, bishops who braved fierce opposition and used threats of excommunication to integrate Catholic schools at a time when many Catholics bucked church teaching on racial equality.

Throughout our history, America's story has been one of an expanding circle of concern embracing human beings once dismissed as unworthy of protection. Given that trajectory, it is reasonable to believe that the struggle to guarantee protection for unborn human lives someday may join the abolitionist and civil-rights efforts as defining movements in our history. If and when that day comes, it will be leaders such as Burke, not their accommodationist critics, upon whom history will smile.