WICHITA, Kan. - A judge ruled yesterday that Kansas law does not allow a so-called necessity defense in the trial of a man charged with killing one of the nation's few late-term abortion providers.

The decision was another blow to lawyers for Scott Roeder, 51, who has confessed in an interview to shooting physician George Tiller on May 31 but has pleaded not guilty, saying the killing was necessary to save "unborn children."

Roeder listened intently, at times twiddling his thumbs nervously under the defense table, as Judge Warren Wilbert gave a lengthy recitation of case precedents that mostly undermined that contention.

In a 1993 criminal-trespassing case involving an abortion clinic, Wilbert said in his ruling, the Kansas Supreme Court said that allowing a person's personal beliefs to justify criminal activity to stop a law-abiding citizen from exercising his rights would "not only lead to chaos but would be tantamount to sanctioning anarchy."

But Wilbert noted that the 1993 case dealt only with property rights, whereas Roeder's case has elevated the argument to whether it is justified to take one life for another. "That is certainly not a position I want to be in - because I am not God," the judge said.

Wilbert said he had heard enough evidence to anticipate what might be presented at Roeder's trial, which is due to begin Jan. 11. He noted that abortion is legal and told attorneys he found it difficult to consider Tiller's slaying at his Wichita church on a Sunday morning, with no overt act by Tiller himself, as an act spurred by an imminent threat of death or bodily harm.

However, Wilbert told attorneys he would "leave the door open" to consider later whether to allow specific evidence on the use of force for the defense of another person before letting the jury hear it.

Roeder now faces life in prison if convicted of first-degree murder. Defense attorneys could later ask the judge to allow jurors to consider a lesser offense such as voluntary manslaughter. A conviction on that charge could bring a prison term closer to five years, depending on prior criminal record.