“On-demand” abortion is a means of distinction from abortions for which the person who wants an abortion tries to “justify” the procedure (e.g., the “hard” cases: rape, incest, infant deformity, maternal life endangerment). When abortion is “on-demand” one is not required to prove a “need.” When abortion is only done in the “hard cases,” the person is expected to furnish proof of “need” (e.g., a physician’s evaluation).
Of course, such a distinction is only helpful in the secular political arena for those who are trying to make a start in stemming the pandemic abortion rate in our country. For the Church, direct abortion either as an end or as a means is never allowed:
“Since the first century the Church has affirmed the moral evil of every procured abortion. This teaching has not changed and remains unchangeable. Direct abortion, that is to say, abortion willed either as an end or a means, is gravely contrary to the moral law” (Catechism of the Catholic Church 2271).
For further reading: