Garry Wills does a nice take down of the contraception kerfuffle.
A few great quotes:
The bishops’ opposition to contraception is not an argument for a “conscience exemption.” It is a way of imposing Catholic requirements on non-Catholics. This is religious dictatorship, not religious freedom.
and
The opposition to contraception has, as I said, no scriptural basis. Pope Pius XIonce said that it did, citing in his encyclical Casti Connubii (1930) the condemnation of Onan for “spilling his seed” rather than impregnating a woman (Genesis 38.9). But later popes had to back off from this claim, since everyone agrees now that Onan’s sin was not carrying out his duty to give his brother an heir (Deuteronomy 25.5-6). Then the “natural law” was fallen back on, saying that the natural purpose of sex is procreation, and any use of it for other purposes is “unnatural.” But a primary natural purpose does not of necessity exclude ancillary advantages. The purpose of eating is to sustain life, but that does not make all eating that is not necessary to subsistence “unnatural.” One can eat, beyond the bare minimum to exist, to express fellowship, as one can have sex, beyond the begetting of a child with each act, to express love.
finally:
When Pius IX condemned democracy and modern science in his Syllabus of Errors (1864), the Catholic historian Lord Acton said that Catholics were too sensible to go crazy every time a pope does.