Sanctity of life is not just the abortion issue, but from the cradle to the grave and includes as mentioned the Death Penalty, Euthanasia, etc. It is also arguable and I agree that it includes such things as defense of the poor, service to the poor and the ill, etc.
For a sin to be mortal three things are required: Grave Offense, Full Knowledge and Full will. There are many who will fail to meet these three conditions due to lack of understanding, lack of education, lack of power, etc.
Emotions often cloud people's judgment in situations dealing with these issues. I am not saying it excuses them in their entirety but this is where the pastoral element must become active, this is why we have such programs as Rachel's Vineyard for those recovering from having an abortion or having participated in them.
While abortion is often argued as "its just a blob", "their life would be ruined", "my parents would kill me", "my boyfriend would leave me" etc, these are considerations that affect a person's ability to reason out their decision and truly understand the ramifications of the act.
Additionally, Capital punishment is easily upheld in an emotional manner because people want revenge, or the perpetrator forfeited their right to life when they took another, etc Doesn't matter, when we execute we remove all chance for redemption, take revenge into our own hands, etc The Church acknowledges the right of the State or Government to utilize capital punishment if it is necessary to protect society, but that with the technology available today there are very few instances when this would be the case, because the perpetrator and society can be sufficiently removed from one another.
Euthanasia is again emotional "I don't want them to suffer", its cruel to make them go through cancer, Lou Gehrigs, MS, Clinical Depression, being brain damaged etc etc. It is through a misguided effort to love that this one takes control. Having lived through the loss of several family members and friends to long term illnesses and also have faced the sudden and unexpected loss of my husband Pete, I can honestly say that those days, even the hard ones with my family members and friends suffering from long term illness were gifts beyond measure, times when all pretense could be stripped away and a true exchange of information and love was possible.
It is good to have the strong guidelines that we do regarding these issues, but we must also keep in mind that for many these times are also confusing, fearful and emotional times which may override what they know or have been taught and for this pastoral love and concern is necessary. Marking no to the sanctity of life question would indicate for me a topic or several actually for discussion and a path through which perhaps I will be the vehicle for a truer understanding of the teaching.