Boston ? There was a moment in Samuel Alito Jr.’s introduction when he tipped his hat to the justice he hopes to succeed. As a rookie arguing his first case before the Supreme Court, Alito remembered, Sandra Day O’Connor’s first question was a gentle one. “I was grateful to her on that happy occasion,” said Alito, “and I’m particularly honored to be nominated for her seat.”

Alito did not mention the time Justice O’Connor was far less gentle, the day she offered a bruising rebuttal to one of his appeals court opinions. But it’s this head-on collision between Alito and O’Connor that tells you what a difference a justice makes.

It tells you as well why pro-life conservatives, who never cottoned up to the “umpire” John Roberts, call this appointment a “grand slam home run.” It tells you why a giddy right-wing Web site, confirmthem.com, is posting the lyrics of a love song, “Alito,” to the tune of “Maria.”

The collision came over Alito’s opinion in Planned Parenthood v. Casey, a case that is becoming the most famous entry in his dossier. The Pennsylvania Legislature had written a slew of restrictions on abortion. But when the law reached the 3rd Circuit appeals court, Alito was the only member who upheld the requirement that a woman must tell her husband before she had an abortion.

Alito argued that most women told their husbands anyway. He brushed aside the idea that this requirement would be a burden on women with abusive husbands. With a wink, a nod, and a footnote, he even implied that the law would be easy to get around, “difficult to enforce and easy to evade.”

The day the case was heard by the Supreme Court, O’Connor cut straight to the heart of the mandated marital talk. If a state could require a woman to notify her husband, she asked, why not her boyfriend or any other man? If a woman had to notify a man before an abortion, could she also be forced to notify a man before intercourse? “Could the state do that?” Where exactly did a woman’s rights end and state rule begin?

The Supreme Court turned out to be far more sensitive to domestic abuse than Alito. “Should these women become pregnant, they may have very good reasons for not wishing to inform their husbands of their decision to obtain an abortion,” wrote the majority.

But O’Connor understood instinctively the relationship between a woman’s right to decide and her individual liberty. The opinion she wrote with Justices Kennedy and Souter said that “the liberty of the woman is at stake in a sense unique to the human condition, and so, unique to the law. … The destiny of the woman must be shaped to a large extent on her own conception of her spiritual imperatives and her place in society.”

The right to abortion itself was upheld 5-4 in Casey. The power of the state to force a marital conversation was denied. It doesn’t take a mathematical genius to see what would have happened with Alito in O’Connor’s seat. Nor does it take a crystal ball to see how far – back – a right-wing court can take us.

For most of history, wives were owned by husbands who controlled all their critical life decisions. Their wages, their property, their bodies all belonged to their husbands. Before Roe v. Wade, women in Pennsylvania who wanted an abortion had to get permission from their husbands as well as a hospital review board. One of those women, Kate Michelman, the former head of NARAL Pro-Choice America, needed consent from the husband who had abandoned her and their three children.

Until 1976, a husband in Missouri could veto a woman’s decision. As recently as 2002, a Pennsylvania man temporarily blocked his ex-girlfriend from getting an abortion.

Legal history shows women gradually gaining their rights as separate individuals, including reproductive rights. Some men protest that they are left with no rights and all the bills. But when push comes to shove, one of two people has to make the decision. Those decisions belong to the one who will bear the child.

Alito’s nomination reminds us that all of this is up for grabs. As Kathryn Kolbert, the attorney who argued Casey in the Supreme Court, says, “To give deference to the rights of legislatures to force women to communicate with husbands is returning them back to the days when they weren’t independent human beings.”

There will be other telltale pages on Alito’s paper trail. But we know what Alito’s 90-year-old mother knows: “Of course he’s against abortion.”

There will be other telltale moments in this presidency, but we now know what happens when the right wing holds a weakened Bush in a vise grip. This is how far we can go.

– Ellen Goodman is a columnist for Washington Post Writers Group.