Elena 
Excerpts from an old debate I had that’s too good to just delete. So I’m putting it here!
The Vatican Council’s declaration on”Religious Freedom” declares that we are bound to follow our conscience faithfully in all our activity, and that no one is to be forced to act in a manner contrary to his conscience. Nor, on the other hand, is he to be restrained from acting in accordance with his conscience, especially in matters of religion. However, The Declaration on Religious Freedom says much more!!
In the formation of their consciences, the Christian faithful ought carefully to attend to the sacred and certain doctrine of the Church.(35) For the Church is, by the will of Christ, the teacher of the truth. It is her duty to give utterance to, and authoritatively to teach, that truth which is Christ Himself, and also to declare and confirm by her authority those principles of the moral order which have their origins in human nature itself. Furthermore, let Christians walk in wisdom in the face of those outside, “in the Holy Spirit, in unaffected love, in the word of truth” (2 Cor. 6:6-7), and let them be about their task of spreading the light of life with all confidence(36) and apostolic courage, even to the shedding of their blood.
He did indeed denounce the unbelief of some who listened to Him, but He left vengeance to God in expectation of the day of judgment.(15) When He sent His Apostles into the world, He said to them: “He who believes and is baptized will be saved. He who does not believe will be condemned” (Mark 16:16). But He Himself, noting that the cockle had been sown amid the wheat, gave orders that both should be allowed to grow until the harvest time, which will come at the end of the world.(16) He refused to be a political messiah, ruling by force:(17) He preferred to call Himself the Son of Man, who came “to serve and to give his life as a ransom for the many” (Mark 10:45). He showed Himself the perfect servant of God,(18) who “does not break the bruised reed nor extinguish the smoking flax” (Matt. 12:20).
Now looking at Father Caprio’s site –
Some Guidelines in Doubtful Situations:
1. A person should not be prevented from following even an erroneous conscience, unless the action is seriously injurious to him or herself, or to others. Thus a person should be prevented from committing suicide if possible, or from killing another person.
2. No one may morally coerce or persuade another to act against his conscience. Thus, the government may not force someone to engage in military service if the person is convinced in conscience that all forms of physical combat are gravely sinful. This principle does not prohibit someone from trying to reason with others in order to make them change their judgement.
AUTHORITY OF THE CHURCH
Are all members of the Church obliged to obey all official moral teachings of the Church and to assume almost as a matter of course that their consciences are necessarily erroneous and not to be followed if they are in conflict with the Church’s moral pronouncement?
DH says:We believe that this one true religion subsists in the Catholic and Apostolic Church, to which the Lord Jesus committed the duty of spreading it abroad among all men. Thus He spoke to the Apostles: “Go, therefore, and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all things whatsoever I have enjoined upon you” (Matt. 28: 19-20). On their part, all men are bound to seek the truth, especially in what concerns God and His Church, and to embrace the truth they come to know, and to hold fast to it.
a. If after appropriate study, reflection and prayer, a person is convinced that his or her conscience is correct (well formed ), the person not only may, but MUST follow the dictates of conscience rather than the teachings of the Church.
b. The Church has never explicitly claimed to speak infallibly on moral questions; so there is probably no question as yet of a conflict between an individuals fallible decision in conscience and a teaching of the Church which is immune from error.
c. No teaching of the Church can hope to account for every moral situation and circumstance. Every teaching still has to be applied in particular cases. One is not necessarily repudiating the values affirmed in the teaching if one decides that the teaching does not bind or apply in this matter.
d. The teachings themselves are historically conditioned. What may have been perceived as morally wrong in one set of circumstances, e.g. charging interest on a loan today, in the context of modern commercial life.
from www.catholic-center.rutge…ience.html
But conscience is no infallible guide. It frequently errs from invincible ignorance (ignorance for which we are not responsible). We Christians search for truth and for the genuine solution of problems in collaboration with others and in fidelity to our own conscience . ( #16 ).
( 1 Tim.1:5). Those who reject a good conscience can make a shipwreck of their faith.
(2 Cor. 4:2) Conscience itself can be weak and even erroneous(1 Cor. 8:10-12).
Because we never know ourselves completely (self knowledge is something one works to acquire; it is not ready made), decisions are necessarily incomplete and partial; and because our own circumstances are always historically, socially and culturally defined, decisions of conscience are necessarily fallible and subject to correction and change. Conscience is never stagnant; it is always in development.