Dr. Susan Robinson

Martha Shane and Lana Wilson talk about their new documentary, “After Tiller,” which explores the subject of third-trimester abortions in the wake of the 2009 assassination of practitioner Dr. George Tiller. They’re joined by Dr. Susan Robinson, a former colleague of Dr. Tiller and one of only four doctors in the United States to perform the procedure. "After Tiller" opens September 20 at Film Forum and at the Film Society of Lincoln Center.

There are nine states that currently allow third trimester abortions without restriction. And — after the murder of Doctor George Tiller in 2009 — only four doctors in the country per...