Sound-bite politics usually make a hash of technical theological distinctions. That's what happened in the recent flurry of reporting and commentary on two sentences penned by Cardinal Joseph Ratzinger in a letter he offered to the U.S. bishops as a "fraternal service," just prior to their June meeting; the letter was intended to clarify the question of a Catholic's worthiness to receive communion.

Here is what Cardinal Ratzinger wrote:

"A Catholic would be guilty of formal cooperation with evil, and so unworthy to present himself for Holy Communion, if he were to deliberately vote for a candidate precisely because of the candidate's permissive stance on abortion or euthanasia. When a Catholic does not share the candidate's stance in favor of abortion or euthanasia, but votes for that candidate for other reasons, it is considered remote material cooperation, which can be permitted in the presence of proportionate reasons."

Applying this, tendentiously, to the question of Catholic voters' responsibilities, the Detroit Free Press concluded that "anti-abortion Catholics can support pro-choice candidates, as long as they agree with the candidate on a range of other issues." The Washington Post headlined its story, "Catholic Voters Given Leeway on Abortion Rights Issue."

Well, not quite.

"Formal cooperation with evil" is a technical phrase, underscoring that the pro-abortion Catholic voter, by embracing the abortion license and furthering it, is thereby cooperating in the death of innocents, which is always gravely evil. Pro-life Catholic voters who vote for pro-abortion candidates despite the candidates' pro-abortion stance do not deliberately advance the death of innocents through abortion (thus "remote material cooperation").

But the crucial questions --- largely missing from press coverage of the cardinal's letter --- remain: When is this morally justifiable? What are the "proportionate reasons" that would lead a pro-life voter to conclude that a pro-abortion candidate's unacceptable position on the life issues can, in effect, be bracketed?

I can imagine one such situation: when the choice is between two pro-abortion candidates, and a voter opts for the pro-abortion candidate of a pro-life party in order to keep that pro-life party in control of Congress. That was the case in my own Congressional district for years. But that is not the situation that Catholic voters face in the current presidential contest or in most Congressional races.

Why does the church stress the priority of the life issues? Because it is always a grave evil to take the life of an innocent human being. Because the rule of law is jeopardized and the public moral culture that makes democracy possible is corrupted when moral wrongs are declared "rights." Because democracy cannot long endure when one class of citizens arrogates to itself the "right" to declare other human beings outside the community of common protection and concern.

That is what the Dred Scott decision did in 1858: it declared Americans of African descent outside the boundaries of the law's protection. That is what Roe v. Wade did in 1973: it declared unborn human beings outside the boundaries of the law's protection. Roe is Dred Scott for our time, because the right-to-life of every human being from conception until natural death is the crucial civil rights issue of our time.

So here's the real question Cardinal Ratzinger's letter raised: What would possibly be the "proportionate reasons" that would cause a Catholic to vote, with a clear and well-formed conscience, for a candidate who's terribly wrong-sided on the great civil rights issue of the day? Because you agree with that candidate on the minimum wage? On the appropriate level of Medicare premiums? On whether the highest federal tax rate should be 36 percent or 38 percent or 40 percent?

In his letter, Cardinal Ratzinger also wrote that "Not all moral issues have the same weight as abortion and euthanasia.... There may be a legitimate diversity of opinion, even among Catholics, about waging war or applying the death penalty, but not, however, with regard to abortion and euthanasia."

The "proportionate reasons" for pro-life Catholics to support pro-abortion candidates must be very, very weighty indeed. Catholics considering a vote for pro-abortion candidates, as well as those who are spinning Cardinal Ratzinger's letter for partisan ends, must define what those reasons would be.

Theirs is a difficult task.

George Weigel is a senior fellow of the Ethics and Public Policy Center in Washington, D.C.