Why Scott Roeder's Defense in Tiller Murder Case Won't Hold Water

Newsweek has a good explanation of why Scott Roeder's attempt to plead voluntary manslaughter in the murder of Dr. George Tiller is unlikely to prevail.

First off, Roeder's admitted actions don't meet the legal criteria:

This means Roeder has to demonstrate not one, but four things. First, that there was a threat to a third person. Second, that the threat was imminent. Third, that imminent threat was the result of an unlawful act. And, fourth, that he honestly believed all of this. If Roeder fails to prove just one, his defense falls apart. Roeder will have to convince the jury that he believed the fetus counts as a "third party"; so far, no state has ever declared a fetus a person. Proving Tiller to have been an imminent threat also poses a challenge, given that he was shot at church, not at his abortion clinic. Even if Roeder could prove that he honestly believed the fetus to be a third party, and that Tiller was indeed an imminent threat, he would still have to convince the jury that he honestly believed Tiller was committing an "unlawful act." Such a belief, however, would have absolutely no basis: despite numerous attempts by former Kansas Attorney General Phil Kline, Tiller was never convicted of performing an "unlawful" abortion. [Newsweek]

The judge has the option of telling the jury to disregard the defense's argument.

However, it's misleading to say that no state has ever declared a fetus a person. Thirty-seven states, including Kansas, have some kind of fetal homicide law, according to the National Council of State Legislators. Generally speaking, these laws treat fetuses as people if they are harmed by a violent crime. That's not the same as full-fledged legal personhood, but it's a troubling step in that direction. Presumably, in Roeder's case the jury would have to decide whether a fetus is a person for the purposes of a voluntary manslaughter defense.