From Pope St. John Paul II’s encyclical Veritatis Splendor (1993):
In order to justify these [modern] positions, some authors have proposed a kind of double status of moral truth. Beyond the doctrinal and abstract level, one would have to acknowledge the priority of a certain more concrete existential consideration. The latter, by taking account of circumstances and the situation, could legitimately be the basis of certain exceptions to the general rule and thus permit one to do in practice and in good conscience what is qualified as intrinsically evil by the moral law. A separation, or even an opposition, is thus established in some cases between the teaching of the precept, which is valid in general, and the norm of the individual conscience, which would in fact make the final decision about what is good and what is evil. On this basis, an attempt is made to legitimize so-called “pastoral” solutions contrary to the teaching of the Magisterium, and to justify a “creative” hermeneutic according to which the moral conscience is in no way obliged, in every case, by a particular negative precept.
No one can fail to realize that these approaches pose a challenge to the very identity of the moral conscience in relation to human freedom and God’s law. Only the clarification made earlier with regard to the relationship, based on truth, between freedom and law makes possible a discernment concerning this “creative” understanding of conscience.
— Veritatis Splendor 56