THE HOUSE of Representatives on Thursday passed a bill that would make it a crime to kill or injure a fetus in the course of committing another federal offense. The bill would, in effect, make hurting or killing a fetus a crime separate from hurting or killing the woman carrying that fetus. The bill is similar to certain state statutes and applies to any "member of the species Homo sapiens, at any stage of development, who is carried in the womb." While the bill specifically exempts abortion, it is a clever, if transparent, effort to establish a foothold in the law for the idea that killing a fetus can be murder.

What makes this bill a bad idea is the very aspect of it that makes it attractive to its supporters: that it treats the fetus as a person separate from the mother, though that same mother has a constitutional right to terminate her pregnancy. This is a useful rhetorical device for the pro-life world. But it is analytically incoherent.

The law cannot hold, at once, that a fetus is fully human for the purpose of federal criminal law yet simultaneously subject to being aborted as a matter of legally enforceable maternal right. Nobody, after all, has a constitutional right to kill another person -- so to the extent that this society has decided to permit abortion, it cannot also offer explicit legal protections to the unborn.

This is not to say that attacks on pregnant women that result in injury or death to their fetuses should not carry increased penalties. Greater sentences seem altogether reasonable, since the damage caused to a woman when a wanted pregnancy is lost is surely greater than in attacks that do not terminate or threaten pregnancies. But the law should not confuse such an increase in sentence with the notion that an offense against the fetus can be severed from the offense against the mother. As the supporters of this bill are well aware, a legal system cannot at the same time guarantee the right to abortion and construe the killing of a fetus as a separate crime.