In Judaism, Pikuach Nefesh (Hebrew: פיקוח נפש) describes the principle in Jewish law that the preservation of human life overrides virtually any other religious consideration. When the life of a specific person is in danger, almost any mitzvah lo ta'aseh (command to not do an action) of the Torah becomes inapplicable.
The Torah, in Leviticus 18:5, states "You shall therefore keep my statutes and my rules; if a person does them, he shall live by them: I am the LORD." The implication here is that Jews should live by Torah law rather than die because of it. Ezekiel 20:11 also states this phrase, "And I gave them my statutes, and showed them my judgments, which if a man do, he shall even live in them."
The Talmud discusses a number of cases as examples in which biblically mandated laws can be disregarded for the sake of saving a human life. (B.Yoma 84b) All of these examples relate to Sabbath prohibitions: rescuing a child from the sea, breaking apart a wall that has collapsed on a child, breaking down a door about to close on an infant, and extinguishing a fire to save a life. The Mishna there discusses when one is permitted to break his or her fast on the Day of Atonement: "If one is seized by a ravenous hunger (ostensibly referring to something life threatening), he may be given to eat even unclean things until his eyes are lightened." (B.Yoma 83a)
The principle of preservation of life, pikuach nefesh, has limitations. The individual whose life is to be saved must be a specific, identifiable individual, rather than an abstract or potential beneficiary.