Some issues allow for a diversity of opinion, and Catholics are permitted leeway in endorsing or opposing particular policies. This is the case with the questions of when to go to war and when to apply the death penalty. Though the Church urges caution regarding both of these issues, it acknowledges that the state has the right to employ them in some circumstances (CCC 2309, 2267).
Pope Benedict XVI, when he was still Joseph Cardinal Ratzinger, spoke of this in a document dealing with when Catholics may receive Communion:
“Not all moral issues have the same moral weight as abortion and euthanasia. For example, if a Catholic were to be at odds with the Holy Father on the application of capital punishment or on the decision to wage war, he would not for that reason be considered unworthy to present himself to receive Holy Communion. While the Church exhorts civil authorities to seek peace, not war, and to exercise discretion and mercy in imposing punishment on criminals, it may still be permissible to take up arms to repel an aggressor or to have recourse to capital punishment. There may be a legitimate diversity of opinion even among Catholics about waging war and applying the death penalty, but not however with regard to abortion and euthanasia” (WRHC 3).The same is true of many other issues that are the subject of political debate: the best way to help the poor, to manage the economy, to protect the environment, to handle immigration, and to provide education, health care and retirement security. Catholics may legitimately take different approaches to these issues while the same cannot be said for euthanasia and abortion, two actions which are always wrong no matter the circumstances. The protection of innocent life always takes precedence to all other issues. What good are all other rights if one does not have the right to life?
Ref: Catholic Answers, Voter’s Guide for Serious Catholics, Catholic Answers Press, 16 pgs, 2016