Tiller, 67, was one of a handful of doctors in the United States to perform abortions into the third trimester of pregnancies. He had been a lightning rod for anti-abortion foes, who nicknamed him "Tiller the baby killer."
His slaying was an act of "domestic terrorism" designed to intimidate other abortion providers, said Terry O'Neill, president of the pro-choice National Organization for Women (NOW).
"Scott Roeder's murder was aimed at other doctors, not just Dr Tiller," she told AFP.
"That's the essence of terrorism."
Roeder has admitted in jailhouse interviews that he shot Tiller but has pleaded not guilty, saying the act was necessary to protect the lives of unborn children.
Jury selection begins Monday.
Tiller's death drew international headlines. Still, it remains unclear what effect, if any, it had in the on-going abortion debate in this country.
O'Neil said Tiller's slaying was "a wake-up call" for many people who had not taken a strong stand on abortion and resulted in a pledge from President Barack Obama's administration to provide greater protection for abortion clinics.
However, the slaying did not appear to influence the debate in Washington over the proposed national health care bill pending in Congress, which in its current form places severe limits on publicly-funded abortions.
And as for lawmakers at the Kansas state level, O'Neill said: "I have not heard of any state legislatures saying we have to protect our (abortion) providers."
Tiller was killed while serving as an usher in the foyer of his church. But the doctor and his clinic, located just off a busy Whichita highway, had been the targets of decades of protests and occasional violence by anti-abortion forces.
To some extent, Roeder's plan worked, O'Neill conceded.
Tiller's family closed the clinic after his death. And a Nebraska doctor initially interested in re-opening it decided against the move in the face of threatened protests.
The head of Operation Rescue, a prominent anti-abortion group that protested at Tiller's clinic for years has denounced the slaying but said it had little effect on the abortion debate.
"There's a pro-life majority in America," he said. "Gallup polls put us over 50 percent. There was a slight dip after Tiller's killing, but it's bounced back. We are the majority, and that's what we're going to be with or without extremists."
As proof, Newman cited the "800-pound gorilla in Washington, the pro-life voting block" that kept abortion funding out of the health care bill.
Roeder, who lived in the Kansas City area, has a long history of anti-abortion activities and, according to one family member, suffers from mental illness.
A judge has already ruled that Roeder cannot pursue the so-called "necessity" defense by arguing that Tiller's death was necessary to save the life of others.
But the judge may permit the defense to introduce evidence of Roeder's beliefs that might allow jurors to consider a lesser crime, such as voluntary manslaughter.
Apparently to that end, Roeder's attorney has subpoenaed Phill Kline, the former Kansas attorney general who aggressively investigated Tiller in an attempt to shut down his clinic.
Before leaving office, Kline charged Tiller with 19 misdemeanor counts, of which a jury quickly acquitted him two months before his murder.
Tiller had become known for providing late-term abortions to women not just in Kansas but from around the United States and the world.
Newman said his organization had no protests planned for Roeder's trial. On his blog, Newman has called Roeder "stupid" for turning Tiller into a "martyr."
O'Neill said NOW members will attend the trial.
"I do think it's important for us to honor Dr. Tiller's courage and, frankly, his martyrdom," she said.
"It appears Scott Roeder is going to try to put Dr. Tiller on trial, and to me that is just monstrous."
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