Antonio Pena and Jaclyn Kurr of Michigan were a turbulent pair. She had sought hospital treatment for injuries he inflicted, and spent time in a domestic violence shelter. Then came their argument about his cocaine use, during which he twice punched her in the stomach.

Kurr did not fear for her life, but warned Pena that she was carrying his babies. She was 16 or 17 weeks pregnant with quadruplets. When Pena seemed about to punch her again, she stabbed him in the chest, fatally. Thus began another awkward episode of living with an abortion culture.

Convicted of voluntary manslaughter, Kurr was sentenced as a habitual offender to five to 20 years’ imprisonment. The trial judge denied her request that the jury be instructed that she had a right to use deadly force in “defense of others,” namely her babies.

The judge ruled that a fetus under 22 weeks old is not “viable,” meaning not capable of surviving outside the mother’s womb. (The noun “mother,” which seems to postulate the existence of an “other” of the sort properly denoted by the noun “baby,” is routinely used in court rulings about abortion.) Therefore, said the judge, there were no “others” to make the “defense of others” rule applicable. He said: “That’s my theory.”

His “theory” is that an unborn baby which has its own unique DNA complex, and which will, absent natural misfortune or deliberate attack (by abortion or someone like Pena) become a born human being is not an “other.” But a Michigan court of appeals disagrees.

It has ordered a new trial, ruling that under Michigan law Kurr had a right to invoke the defense of “others.” The appeals court noted that in 1998, Michigan’s Legislature adopted a fetal defense act which does not distinguish between viable and nonviable fetuses and says it is a crime to cause a miscarriage or stillbirth while acting “in wanton or willful disregard of the likelihood that the natural tendency of” such conduct is to cause a miscarriage or stillbirth.

The appeals court said the Legislature plainly believes “that fetuses are worthy of protection as living entities.” About half the states have such laws. But given the U.S. Supreme Court’s 1973 ruling in Roe vs. Wade, states can treat fetuses as worthy of protection from people like Pena, but not from their mothers. The “defense of others” doctrine allows an individual to protect an unborn baby only from unlawful violence, which does not include abortion.

There have been many cases illustrating the impossibility of reconciling an abortion culture the right of unlimited abortion on demand and moral judgments of the sort expressed in Michigan law. In Texas, a drunken driver who struck a pregnant woman’s car was convicted of killing the woman’s baby, which did not survive after being born a month and a half prematurely. A Baltimore court in effect took custody of a fetus by placing a pregnant drug abuser under court jurisdiction to prevent her from jeopardizing the health of her fetus unless she exercised her right to kill it by abortion.

Abortion kills something. What is it? A television commercial for General Electric’s new ultrasound system shows a pregnant woman and her husband marveling at an amazingly clear picture of their unborn baby’s features. The commercial features Roberta Flack’s song “The First Time Ever I Saw Your Face.” The announcer says: “When you see your baby for the first time on the new GE 4D ultrasound system it really is a miracle.”

By the time babies are as old as Kurr’s quadruplets were, ultrasound can show their fingers and beating hearts. The Supreme Court in Roe called such babies “potential life,” a weird opinion that could be forgiven if this were the 11th century, knowing nothing of embryology or microbiology if the beginning of life were a matter of uninformed conjecture.

Today doctors perform wonders of prenatal diagnostic and therapeutic medicine, administering drugs and blood transfusions and performing surgery in utero treating as patients fetuses that mothers have a right to kill. Many expectant couples have, in the nurseries they have prepared for their “potential” babies, framed ultrasound photographs of the “potential” babies. Many couples have fetal heartbeat stethoscopes for listening to what? “potential” heartbeats?

A few weeks after being punched by Pena, Kurr miscarried. Whether the punches caused the miscarriage is unclear. She had a constitutional right her privacy right of “choice” to kill the unborn babies. And in Michigan and many other states she could kill someone who endangered them. That’s the law.

George Will is a columnist for Washington Post Writers Group.