Roman Catholic teaching on the primacy of conscience in matters of faith and morals is unequivocal: the person is alone with God to listen to God in examining conscience.
The Church's official teaching, the collective but sometimes fallible wisdom of the Church in matters Ordinary, is secondary.
Primacy of conscience goes directly to the question, what does it mean to be Roman Catholic?
Consider the following real life scenario:
A woman decides as a matter of conscience to keep her life for her six healthy living children rather than sacrifice her life for her unborn twins, one of whom now dead will poison her to death in days. It is the beginning of the ninth month. Both fetuses are seriously deformed. The other twin alive but expected to die a painful death within hours of delivery.
Surely in the eyes of a merciful Church she has committed no sin in choosing her life over death in this tragic and painful circumstance.