The Catechism in Questions & Answers

333. What is the significance of the Fifth Commandment for us today?

The beginning and end of human life lies in the hand of God alone. Only He is Lord over life and death.
This commandment continues to apply today even though violence often prevails on earth and though many people have little regard for the lives of others. In addition to the prohibition against terminating human life, it also implies a duty to respect, protect, and preserve human life.
Any violation of the Fifth Commandment is sin. The guilt before God resulting from it may vary (cf. Question 230).