The Nebraska statute prohibited "partial birth abortion", which it defined as any abortion in which the physician "partially delivers vaginally a living unborn child before killing the unborn child and completing the delivery." The most common type of abortion performed is suction-aspiration abortion which consists of a vacuum tube inserted into the uterus; others consist of what is known as "D&E" (dilation and evacuation), which is usually used during the second trimester because of the increased amount of fetal material. The procedure dilates the cervix and removes some fetal material with non-vacuum instruments, and, in some cases, uses curettage inside the uterus so that fetal material can be evacuated. Dr. Carhart wanted to use a modified version of this called "D&X" (Dilation and Extraction), which, rather than commencing curettage inside the uterus, extracts part of the fetus first and then begins the process of dismemberment. Carhart stated that he wanted to perform this procedure because he believed it would be safer and would involve fewer risks for the women; it lowered the risk of leaving potentially harmful fetal tissue in the uterus, and it minimized the number of instruments physicians needed to use.
Experts in fetal development provide markedly different assessments of the kind and degree of pain (if any) experienced by the fetus (see Fetal pain). Although in the second and third trimesters the nervous system is largely in place, the level of consciousness or awareness of the fetus is a matter of conjecture. Experiments aimed at measuring fetal pain have yielded results that are somewhat open to interpretation, given that measurable reactions of the fetus to stimuli may not correspond directly to an adult experience of pain. Many medical authorities affirm that at the stage of pregnancy when this procedure is performed, the fetus has not reached what the medical community has defined as viability, the stage at which a developing fetus can be expected to live if removed from the uterus (usually at five months gestation, with medical assistance, although the viability threshold is retreating with medical advances).
The medical and scientific questions surrounding partial-birth abortion are impacted in the public arena by political and special interest considerations, resulting in a certain degree of media "hype" surrounding this case. Proponents of abortion rights on the one hand and the right-to-life on the other both decry what they describe as "myths" regarding this procedure that have passed into mainstream American debate on the issue.
The fetus, in many cases, dies just as a human adult or child would: It bleeds to death as it is torn from limb from limb. The fetus can be alive at the beginning of the dismemberment process and can survive for a time while its limbs are being torn off.
This was a far cry from Justice Clarence Thomas' dissent, which stated that abortion was not a right contained in the Constitution, and sharply criticized the majority and concurring opinions. Chief Justice William Rehnquist, along with Antonin Scalia, and Thomas have consistently said that they do not believe abortion is a protected right, and have pointed out that "privacy" is not explicitly mentioned in the Constitution. Thomas also pointed out in his dissenting opinion that even if abortion was a woman's right, the law in question was not designed to strike at the right itself. He reminded the others that many groups, including even the American Medical Association, had concluded that partial-birth abortion was very different from other forms of abortion, and was often considered infanticide. Thomas further noted that the gruesome nature of some partial-birth abortions has caused personal trauma in the doctors performing them. In a short separate opinion, Chief Justice Rehnquist stated that he did not join Casey but felt that Justice Kennedy had applied its precedent correctly, and thus joined his opinion.
In his dissent, Justice Scalia recalled his prior dissent in Casey in which he had criticized the undue burden standard as "doubtful in application as it is unprincipled in origin." What constitutes an undue burden is a value judgment, argued Scalia; it should therefore be no surprise that the Court split on whether the Nebraska statute constitutes an undue burden. Scalia moreover chastised Kennedy for feeling betrayed by the majority. Scalia declared that the Stenberg decision was not "a regrettable misapplication of Casey,"—as Kennedy claimed—but "Casey's logical and entirely predictable consequence." Denouncing the undue burden standard of Casey as illegitimate, Scalia called for Casey to be overruled.
By a 5-4 majority, the Nebraska law was struck down, as were all other state laws banning partial-birth abortion. In 2003, however, the federal government enacted a Partial-Birth Abortion Ban Act. This law did not include an exception for the health of the mother, as Justice O'Connor said it must. Congress inserted "findings" into the law saying that the procedure is never needed to protect maternal health. Although several federal judges struck down this federal law, citing the precedent of Stenberg v. Carhart, it was eventually upheld by the Supreme Court in Gonzales v. Carhart.
The Supreme Court case of Gonzales v. Carhart concerns similar questions as those in Stenberg, but this time in the context of a federal statute. Since Stenberg, Chief Justice John Roberts and Justice Samuel Alito have been confirmed. The decision in Gonzales v. Carhart has greatly narrowed the holding in this case.