If lying is always morally wrong, then it must follow that it can never be morally justified to do it, for whatever reason, so says the Catechism. (CCC 1753)
This is so “sola scriptura”-like and simplistic to be laughable. Just like we rightly criticize those who take Scripture out of context, so must we criticize this.
First of all, when one is under duress one is give the moral authority to take reasonable steps to remove themselves from teh duress. This includes lying to one who has a gun pointed at our head.
Secondly, CC1753 is out of context when under duress or one is questioned by one who has not right to the truth.
Thirdly, one needs to remember CCC-2488 The right to the communication of the truth is not unconditional. Everyone must conform his life to the Gospel precept of fraternal love. This requires us in concrete situations to judge whether or not it is appropriate to reveal the truth to someone who asks for it.
Additionally, one needs to study the “Double Effect Theory” which I believe was first articulated by St. Thomas Aquinas but is used by the Church when justifying matters like self-defense, just war, and certain medical procedures to protect life. In most of the examples on this thread, the concept is applicable here.
Also, if all the answers for all situations could be found in Scripture and the Catechism, there would be no need for conscience and the exercise of our prudential judgment. These significant gifts from God that separate us from the animals and not to be minimized or trivialized.
Finally, I refer you to the section of the CCC on Sin (1846-1869) which introduces the concepts of:
*]Sin is a failure in love of God- Protecting the lives of others from evildoers is consistent w/ our call to love and follow God
*]Sin is a lack of charity- Placing one in harm for another or protecting another’s well-being is an act of charity
*]Consent- Without consent or freedom (ie duress) there is no sin