In the 1990s, pro-lifers have used fetal diagrams to illustrate the horror of partial birth abortions.
Pro-lifers have never used diagrams when protesting partial birth abortions. 
mnli hypothesis: Pro-lifers have never used diagrams when protesting partial birth abortions.  premise: In the 1990s, pro-lifers have used fetal diagrams to illustrate the horror of partial birth abortions.