By the end of the year, the Michigan Supreme Court may take up a case that has already reignited the age-old debate of when life begins.

The case involves Jaclyn Kurr, who was 17 weeks pregnant when she stabbed and killed her boyfriend, Antonio Pena, in October of 1999, after he punched her in the stomach. She later had a miscarriage.

Found guilty of manslaughter, Kurr is now serving a prison term of five to 20 years.

During her trial, Kurr's attorney, Gail Rodwan, argued that her client had the right to defend herself and her fetus, under a statute in Michigan called the defense of others law. It says, in part, that a "person has the right to use force or even take a life to defend someone else under certain circumstances if a person acts in lawful defense of another."

"Mr. Pena struck her in the stomach with his fist and that was what prompted her defensive action … the fetus is not in a position to protect itself," Rodwan told Fox News.

But during Kurr's trial, the judge barred the jury from considering this argument after hearing medical testimony from a physician that a fetus isn't viable until 22 weeks, which Kurr's fetus was not. The judge concluded that in order for Kurr to present a "defense of others" theory, there had "to be a living human being existing independent" of Kurr.

Last month, a state court of appeals overturned Kurr's conviction on the grounds that the jury was not properly instructed on the "defense of others" theory.

The case has been appealed to the Michigan Supreme Court, which is weighing whether to take the case and delve into the controversy of when a fetus actually becomes viable.

"It is going to open up the entire question of what is an embryo, what is life? When does it begin?" said John Mayoue, a Georgia attorney who specializes in fetus rights. He said he's concerned that Michigan may set a dangerous precedent if the court decides a mother has the right to kill in order to protect the unborn.

"I think the case opens some very difficult, complex questions because in Michigan what we are now saying is that I can kill someone if I am pregnant who is trying to harm the fetus, whether the fetus is viable or not," Mayoue said. "What's most interesting about that, the very next day after I have killed the person who tried to harm my fetus, I can turn around and abort it without any legal consequences whatsoever."

But Kurr's attorney said the case has nothing to do with abortion.

"We are not addressing abortion questions," Rodwan said. "We are addressing a very narrow issue when a pregnant woman is assaulted, does she have the right to protect the fetus."

There is also a fetus protection law on the books in Michigan. It says a fetus is entitled to separate protection and that a person that assaults a pregnant woman may be criminally liable for any harm to that woman or her unborn child.

The U.S. Supreme Court has ruled that a pre-viable fetus is not a person. That means the federal government considers life to begin only when a fetus is capable of surviving and developing outside of the mother's womb on its own. Under current law, when an unborn victim is murdered or killed, such as when the mother is attacked or assaulted, no one is deemed to have died. Therefore, prosecutors cannot charge the person responsible for the fetus' death.

One U.S. House lawmaker tried last year to make it a national law to criminalize someone causing harm to an unborn child.

U.S. Rep. Lindsey Graham, R-S.C., introduced the Unborn Victims of Violence Act, which would have established criminal penalties for someone who, while committing any one of a series of federal crimes, causes death or injury to a "child who is in utero at the time the conduct takes place." The House passed the bill, but it didn't make it out of the Senate.

Various state courts have also taken up the issue of when a fetus is viable.

Michigan may soon reconsider this controversy if the state Supreme Court decides to hear Jaclyn Kurr's case.

Until then, Kurr remains behind bars. Her fate, and the possibility of a new trial, are still up in the air.

Fox News' Liza Porteus contributed to this story.