Once again, a politician has gotten tripped up talking about abortion. Senator Barack Obama’s recent comments on late-term abortion have him defending charges from some progressives that he’s moving right in order to appeal to swing voters, while fighting off attempts from conservatives to paint him as the “abortion candidate.”

Of course, it’s no coincidence that politicians are constantly asked about late-term abortion. When, if ever, do we talk about first-trimester abortion, which accounts for almost 90 percent of all abortions in this country? When do we get to talk about much more common reproductive health care needs–like prenatal care, HIV/AIDS and other sexually transmitted infections? What about breast and cervical cancer?

The answer is “rarely,” and there’s a reason why. In the 1990s, anti-abortion rights activists identified an extremely effective strategy when they crafted their campaign against what they called “ partial-birth abortion.” By describing it as if it were being performed on fully developed, viable fetuses, they connected abortion to infanticide in people’s minds.

They ignored the fact that the procedure (before Congress banned it) was used primarily around the midpoint of pregnancy, well before a fetus could survive outside the womb, and that no type of abortion is performed in this country after a fetus is viable, unless there is a medical reason.

But by conjuring up the specter of infanticide, opponents of abortion rights have been able to exploit the ambivalent feelings most Americans have about abortion. Americans’ support for abortion varies tremendously based on the point in time at which it occurs: the farther a pregnancy progresses, the less comfortable most people are with allowing abortion.

This position is understandable, given the general agreement that the value of embryonic and fetal life increases over time and the reflection of that sentiment in the legal framework set out in Roe v. Wade, the Supreme Court case that legalized abortion.

This view is complicated, however, by the fact that Americans often make a distinction between circumstances they think justify abortion and those they do not. Interestingly, those opinions tend to line up with women who are seen as “deserving” of an abortion and those who are not. There is widespread support for abortion when a woman has suffered rape, incest or threats to her life or health–in other words, circumstances that are seen as “beyond her control.” But support falls sharply when socio-economic reasons are cited as the cause. Then the woman is viewed as “shirking responsibility,” “avoiding the consequences,” or “getting away with it.”

But what exactly is she getting away with? Having sex? Not using or misusing contraception? Getting pregnant accidentally? Pursuing her education or career? Meeting the emotional and financial needs of children she already has?

The bottom line is, judgments about abortion reflect our societal judgments about women and whether we trust them to make good decisions. The dispute over a mental health justification for abortion, of which Senator Obama has found himself at the center, is precisely about whether we believe a woman is truly struggling with a mental health problem that justifies her abortion or whether she has come up with “an excuse” in order to terminate her pregnancy.

If we trusted women to bring an appropriate moral weight to the decision to end a pregnancy, if we put our faith in a woman’s own determination of when an abortion is necessary in her life, if we believed a woman’s life is ultimately more important than the one developing inside her and if we recognized that her right to live her life according to her own conscience trumps our opinions about what we think we would do in her situation, then we would not even be having this conversation.

Just 11 percent of all abortions in this country happen after the twelfth week of pregnancy and only 1 percent occur after twenty-one weeks. Yet we seem to spend 99 percent of our time talking about “late-term” abortion, which almost never gets defined. The reason, as far as I see it, is because abortion-rights opponents have no incentive to give up such a powerful tool in their fight to criminalize all abortions.

The debate over late-term abortion has lasted long enough. It is a straw man designed to undermine our trust in women. When progressives are asked to defend what is presented as the indefensible, all they need do is defend women themselves.