KANSAS CITY, Mo. — Privacy is the great American assumption.

Even though the word is absent from the U.S. Constitution, lawyers find its spirit in the First, Third, Fourth, Fifth, Ninth and 14th amendments. No less than the U.S. Supreme Court has insisted the Constitution brims with the right to privacy.

Yet doubters say a right to privacy can't be discovered in the document merely by wishing it were there.

So when justice nominee Harriet Miers submits to her grilling on Capitol Hill, senators will be particularly curious about what she thinks of privacy, especially whether it guarantees women the right to abortion.

Meantime, the judges she hopes to join are contemplating whether privacy means the terminally ill in Oregon can commit suicide with the aid of a doctor. In Congress, lawmakers debate whether privacy should warrant a different priority in the post-Sept. 11 world. And the practical problem of keeping confidences could disappear one computer click at a time, with everything from e-mail musings to medical histories vulnerable.

In short, the national expectation of privacy is revised by judges, contested by politicians and imperiled by technology.

"Anyone within the broad mainstream agrees that there are some privacy rights in the Constitution," said Pamela Karlan, a Stanford University law professor. "After that, it gets harder to find common ground."

Claims of privacy figure across a wide swath of hot-button conflicts. Few compare with abortion or physician-assisted suicide, but the privacy debate stretches deep into the national conversation.

When Chicago and a group of shooting victims sued firearms manufacturers, the federal government and the National Rifle Association cited privacy to keep records of gun purchases under wraps. Lower courts ruled that the city's interests trumped privacy worries. After the high court agreed to hear the case, Congress passed a law effectively cloaking the records, and an appeals court this month defended that action.

The U.S. Supreme Court struck down a Texas law against sodomy and its own earlier rulings in a 2003 case, ruling that "liberty protected by the Constitution allows homosexual persons the right to choose to enter upon relationships in the confines of their homes and their own private lives."

When the Clinton administration in 2000 proposed rules for applying wiretap rules to e-mail, Congress rejected the plan because it granted too little privacy. Barely a week after the attacks of Sept. 11, 2001, the Patriot Act gave government much-easier access to wholesale perusal of e-mail.

Were the Constitution drafted today, most scholars think its reference to privacy would be explicit. But 200 years ago, the issues where it pops up weren't as common. The ways in which we can eavesdrop on each other or regulate each other's personal behavior had yet to exist.

The Supreme Court recognized privacy as constitutionally sacred in a 1965 case involving a family-planning clinic prosecuted for distributing contraceptives. Writing for the majority in Griswold v. Connecticut, Justice William O. Douglas conceded that privacy isn't spelled out in the Constitution. But he found it is "so rooted in the traditions and conscience of our people as to be ranked as fundamental" and said couples should enjoy the privacy to do largely as they wish in their bedrooms.

In dissenting, Justice Hugo Black launched a complaint still echoing today about the dangers of "judicial activism." Black found the law against contraception offensive but blasted his colleagues' imagining a right of privacy. "I like my privacy as well as the next one," he wrote, but "the government has the right to invade it unless prohibited by some specific constitutional provision."

With that case, experts say, privacy began to mean not just freedom from snooping, it also meant autonomy — that is, privacy as defined by the ability to keep government from regulating private behavior.

In 1973, the court cited the same sense of autonomous privacy in the Roe v. Wade case that granted women the right to an abortion. That further inflamed court critics, who said the justices were using a right only implicit in the Constitution to inflate an argument for something else — abortion — that the founders didn't contemplate.

While some abortion-rights advocates concede they'd rather have their legal standing anchored in a right more clearly spelled out in the Constitution, the resiliency of the Roe case has given the movement confidence in the legal argument.

"There is no stronger basis than the basis on which Roe was decided," said Blake Cornish, legal director for NARAL Pro-Choice America. "Reproductive choice is so fully a part of the law now, and that's because of privacy."

At the libertarian Cato Institute, vice president for legal affairs Roger Pilon said Roe distorted the idea of privacy for political convenience: "It talked about privacy for the right of the mother, ignoring the question of whether the unborn child has rights."

Eugene Volokh, a University of California, Los Angeles, law professor, said that regardless of legal definitions, technology has made information that was nearly private more easily public.

For instance, many government documents containing personal information have long been technically public records but were so difficult to access that they were effectively secret. Now many of those records full of addresses, birth dates and property ownership are available on the Internet, causing some people to call for another rethinking of privacy rights.