The debate over Judge John Roberts’s nomination to the Supreme Court has alternated between speculation about whether he would vote to overrule Roe v. Wade and reassurances that he might not–or, at any rate, that his position on the case would not decide its fate. But for those concerned about women’s lives rather than legal abstractions, the crucial issue is being overlooked: To place the lives and health of millions of women at risk, Roberts need not oppose Roe v. Wade itself; his interpretation of its protections need only be slightly more conservative than that of Justice Sandra Day O’Connor’s.

To be sure, there is ample evidence that Roberts would follow the model of Chief Justice Rehnquist, for whom he clerked, and vote to overrule Roe outright. Roberts, after all, urged the Court to do precisely that when he served in the George H.W. Bush Administration. But focusing the debate exclusively on the survival of Roe itself allows Roberts to hide in the shadows of speculative questions–even though his patently clear conservatism is considerable cause for concern.

It’s technically accurate, though hardly reassuring, that Roe could survive Roberts’s opposition by a 5-to-4 majority. But while six sitting Justices do support Roe, only five–including O’Connor–have reliably voted to strike down severe restrictions on reproductive choice. The so-called “partial-birth abortion” ban–a misnamed law so recklessly written that it amounts to a widespread ban on a variety of abortion procedures–is an important case in point. The Court has struck down such bans in the past on the grounds that they didn’t protect a woman’s health, with O’Connor providing a critical vote for the five-Justice majority. The Supreme Court will soon be asked to review the constitutionality of a new federal “partial-birth abortion” ban that contains no meaningful health exception. Roberts, if confirmed, likely would cast the deciding vote.

Another case already pending before the Court deals with New Hampshire’s law requiring that a parent be informed of a minor’s decision to have an abortion, even if the abortion is needed to protect the minor’s health. Roberts’s vote in this case could create a wide-ranging precedent. Under Roe as initially decided, restrictions on pre-viability abortions had to be justified by a “compelling state interest.” While on the Court, O’Connor was the architect of a new legal standard that left Roe and reproductive privacy nominally intact but significantly lowered their protections, permitting restrictions on abortion provided they did not constitute an “undue burden” on women. That murky standard, which leaves great discretion to lower-court judges, has allowed a broad array of state restrictions. Only a few–such as the “partial-birth abortion” bans–have been held to present an undue burden for a significant proportion of women. New Hampshire seeks to weaken even that fragile standard by permitting restrictions unless they would present an undue burden to women in every conceivable application. Such a precedent would eviscerate what is left of Roe. Women’s circumstances–including their health–vary so substantially that such generalizations would be impossible. Practically speaking, the door to any restriction on a woman’s right to choose would be unbarred.

Only O’Connor’s vote has protected the undue-burden standard. Justice Anthony Kennedy, who shocked observers by voting to uphold Roe, has also held to a far narrower view of its protections–voting, for example, with Scalia, Thomas and Rehnquist to uphold the Nebraska “partial-birth abortion” ban. With one more ally, their bloc would become a majority. Whether Roberts is an inch to O’Connor’s right or a mile, Roe could become functionally meaningless.

Based on the thousands of pages of records that paint Roberts as a clear legal architect of the Reagan and Bush strategies to limit civil rights, it seems quite plausible that he is as conservative as Scalia, Thomas and Rehnquist. But the fact that he crosses the critical threshold–being more conservative than O’Connor–is beyond doubt. Many observers note that there is no guarantee Roberts would be a conservative on the Court. To accept that reassurance, one must make the dubious assumption that the record he has compiled as both a practitioner and a judge is but a prelude to the complete reversal that awaits. The choice, then, is to believe Roberts has executed what must rank as one of history’s greatest and longest-running political deceptions, or simply to take a man widely admired for his integrity at his word–namely, that he is a judicial conservative. That is neither an epithet nor an insult; it is simply an accurate description of his philosophy.

Senators must explore whether Roberts believes the requirements of stare decisis (respecting and adhering to precedent), about which he has spoken approvingly, are satisfied by upholding a right in name only if its core protections are gutted. Moreover, does Roberts believe the Court should decide cases of individual rights based on the number of individuals at stake and uphold laws on the theory they deprive “only” some, but not all, women of their health and liberty?

Senators have the right–and responsibility–to evaluate Roberts as President Bush did: on the basis of his judicial philosophy and legal views. But it is equally imperative that they frame the issues properly. If the debate about personal privacy and reproductive rights is limited to whether Roberts will vote to overturn Roe, it will raise a vital question but almost certainly fail, at least decisively, to answer it. But senators can easily ascertain whether Roberts stands to O’Connor’s right, and that alone provides ample reason to worry. By all indications Roberts might vote to overrule Roe. To imperil the lives and rights of millions of women, he would not have to. Roberts need only vote like a shadow of the conservative he’s always claimed to be.