The Sixth Commandment – mistranslated as “Thou Shall Not Kill (Ratsach, Murder)”
The death penalty is an integral part of the Old Testament Law. It is in all five books of Moses (Genesis-Deuteronomy), and in other books of the Old Testament as well. Furthermore, the New Testament supports it. The most common reason why people believe the Bible does not support the death penalty is because the King James Version and the versions of the Bible read by most Roman Catholics (including the Douay Version, The New Jerusalem Bible, and the New American Bible) give the Sixth Commandment in Exodus 20:13 and Deuteronomy 5:17 as, “Thou shalt not kill.” The Hebrew word translated “kill” in the Sixth Commandment is ratsach, and it can mean “kill” or “slay,” either on purpose or accidentally.
Ratsach, like many other words, has a wide range of meaning, and thus its meaning in a particular verse must be determined from both the immediate and remoter contexts. Thankfully, the Bible has a lot to say about murder, manslaughter, the execution of criminals and killing in war, and it is easy to tell by studying all the verses on the subject that the Sixth Commandment means not to take a life unjustly. Bible commentators are not confused by the commandment, “You shall not kill.” Maxie Dunnam wrote about the Sixth Commandment in the Mastering the Old Testament commentary on Exodus:
According to Genesis 9:6, this commandment did not prohibit the death penalty. It is obvious in the Old Testament that this [Sixth Commandment] was not a prohibition against all killing, only unauthorized killing. 
Because the Bible has clear teaching on murder and manslaughter, and because saying, “You shall not kill,” confuses people about killing in self-defense, in war and the execution of criminals, most modern versions properly translate ratsach in the Sixth Commandment as “murder.” For example:
- New King James Version: You shall not murder.
- Revised English Bible: Do not commit murder.
- New International Version: You shall not murder.
- New American Standard Bible: You shall not murder.
- New Revised Standard Version: You shall not murder.
- Amplified Bible: You shall not commit murder.
- New English Bible: You shall not commit murder.
- Tanakh (Jewish Publication Society): You shall not murder.
The above versions of the Bible were produced by teams of scholars with differing theological backgrounds, including Protestant, Anglican, Roman Catholic, Orthodox, and Jewish scholars. It should be clear from the evidence that the Sixth Commandment is not about the death penalty, but about unjust killing, that is, murder.
Although the best single-word translation of the Hebrew word ratsach in the Sixth Commandment is “murder,” ratsach does have a wider application that must be considered. The well-known Hebrew scholars C.F. Keil and Franz Delitzsch write:
Accordingly, in the command, “Thou shalt not kill,” not only is the accomplished fact of murder condemned, whether it proceed from open violence or stratagem (Chap. 21:12,14,18), but every act that endangers human life, whether it arise from carelessness (Deut. 22:8), or wantonness (Lev. 19:14), or from hatred, anger and revenge (Lev. 19:17,18). Life is placed at the head of these commandments, not as being the highest earthly possession, but because it is the basis of human existence, and in the life the personality is attacked, and in that the image of God (Gen. 9:6). The omission of the object [of the verb ratsach] still remains to be noticed, as showing that the prohibition includes not only the killing of a fellow-man, but the destruction of one’s own life, or suicide. 
The highly respected commentator Adam Clarke wrote specifically about the Sixth Commandment in his six-volume commentary on the Bible:
Thou shalt not kill. This commandment, which is general, prohibits murder of every kind. 1. All actions by which the lives of our fellow creatures may be abridged. 2. All wars for extending empire, commerce, etc. 3. All sanguinary laws, by the operation of which the lives of men may be taken away for offences of comparatively trifling demerit. 4. All bad dispositions which lead men to wish evil to, or meditate mischief against, one another; for, says the Scripture, he that hateth his brother in his heart is a murderer. 5. All want of charity to the helpless and distressed; for he who has it in his power to save the life of another by a timely application of succour, food, raiment, etc., and does not do it, and the life of the person either falls or is abridged on this account, is in the sight of God a murderer. He who neglects to save life is, according to an incontrovertible maxim in law, the same as he who takes it away. 6. All riot and excess, all drunkenness and gluttony, all inactivity and slothfulness, and all superstitious mortifications and self denials, by which life may be destroyed or shortened; all these are point blank sins against the Sixth Commandment [emphasis his]. 
Adam Clarke is correct when he says that the Sixth Commandment prohibits murder of every kind. It has nothing to do with the death penalty, but is a command not to murder or kill another man unjustly. The vast majority of modern versions recognize this, and read “You shall not murder.” Since killing in criminal execution, in self defense, and in war are condoned in Scripture, it is hard to see how “You shall not kill” is an acceptable translation of ratsach in the Sixth Commandment. There is no question that the average reader gets the wrong idea from that translation. Instead of correctly concluding that accidental killing and suicide are being included with murder, the modern reader wrongly concludes that self-defense, the execution of criminals, and killing in war are forbidden by God. Thus, the majority of modern translators have chosen to translate the verse as “You shall not murder” because that communicates to modern Americans. Perhaps an alternative translation which includes the word “kill” would be, “You shall not kill unjustly.”
As Clarke, Keil, and Delitzsch, quoted above, point out, the Sixth Commandment also prohibits the taking of a life through carelessness or wantonness. The thought that God is prohibiting “accidental killing” can be confusing at first, because “accidents happen.” However, a quick review of the history of mankind will clearly show that a lot of “accidental deaths” could have been prevented if people had cared more about their own lives and the lives of others. Accidental deaths often occur in an environment that could have been made safe if proper attention had been paid to safety. We will never be able to assure perfect safety for people, but things could be a lot safer than they are if human life were more highly valued.
 Maxie Dunnam, Mastering the Old Testament, Exodus (Word Publishing, Dallas, 1987), p. 263.
 C.F.Keil and F. Delitzsch, Commentary on the Old Testament, The Pentateuch (William B. Eerdmans, Grand Rapids, reprinted July, 1976), Vol. 1, Book II, pp. 123,124, note on Exodus 20:13.
 Adam Clarke, The Holy Bible with a Commentary and Critical Notes, A New Edition with the Authors Final Corrections (Abingdon Press, Nashville), Vol. 1, pp. 405,406.