ends and means

A recent study supports the popular opinion (used to justify the HHS birth control mandate, among other things) that providing free contraceptives to women reduces the rate of abortion:

Free birth control led to greatly lower rates of abortions and births to teenagers, a large study concludes, offering strong evidence for how a bitterly contested Obama administration policy could benefit women’s health. The two-year project tracked more than 9,000 women in St. Louis, many of them poor or uninsured, who were given their choice of a range of free contraceptives.

– Quote from NYT, based on findings in this study.

People infer that the Catholic Church is 'wrong about contraception' and should accept contraception because free contraceptives are proven to reduce abortions and unwanted pregnancies.

Thomas Aquinas, on whether the ends justify the means:

On the contrary, Boethius says (De Differ. Topic. ii) that "if the end is good, the thing is good, and if the end be evil, the thing also is evil."

That is a simple way of stating it, but he elaborates:

Nothing hinders an action that is good in one of the way mentioned above, from lacking goodness in another way. And thus it may happen that an action which is good in its species or in its circumstances is ordained to an evil end, or vice versa. However, an action is not good simply, unless it is good in all those ways: since "evil results from any single defect, but good from the complete cause," as Dionysius says (Div. Nom. iv).