Supreme Court justices returned to the controversial issue of abortion Wednesday, weighing arguments on whether a procedure critics call "partial-birth" abortion can be banned constitutionally.

U.S. Solicitor General Paul D. Clement, arguing for the Bush administration in back-to-back cases, said the procedure is "something that is far too close to infanticide for society to tolerate."

Attorney Eve Gartner, representing the Planned Parenthood Federation of America, argued the procedure is sometimes necessary to protect a woman's health. "It averts catastrophic health consequences in some circumstances," she said.

The two-hour discussion of pros and cons of the procedure — medically known as intact dilation and evacuation — prompted justices to deal with both legal and medical questions. During the rarely used procedure, which occurs in the second or third trimester of pregnancy, a fetus is partially extracted through the birth canal and its skull is collapsed by suctioning out the brain.

One key question in the case is whether it is ever necessary. Clement argued that it is not, while the lawyers on the other side said it can be. The case reached the high court after two lower courts rejected the 2003 Partial-Birth Abortion Ban Act because the ban did not include a medical exception for the mother.

The two cases, Gonzales v. Carhart and Gonzales v. Planned Parenthood, were appealed from the 8th Circuit Court of Appeals and the 9th Circuit, respectively.

While ban opponents worry that the measure could reduce the rights of women to abortion that were gained in the 1973 Roe v. Wade decision, Clement, defending the government, said it is focused on a certain procedure.

"Congress didn't go after the dog, so to speak," he ...