Rambam - 1 Chapter a Day

Our translation follows the standard version of the Mishneh Torah, from which one might infer that it is forbidden to kill a gentile as well. Although killing him does not warrant capital punishment, it is forbidden by Scriptural Law. It must, however, be noted that authoritative manuscripts and early printings of the Mishneh Torah state “Whenever a person kills a Jewish man....”

Sefer HaMitzvot (Negative Commandment 289) and Sefer HaChinuch (Mitzvah 34) regard this as one of the Torah’s 613 commandments.

As explained in Hilchot Sanhedrin 15:4, this refers to decapitation as practiced by the gentile kings.

I.e., we do not say that since a person killed a colleague by fire, he should be executed by being burned to death.

This is speaking about an instance where the murderer acted intentionally. If a person kills unintentionally, the Rambam rules (Chapter 5, Halachah 10) that it is not a mitzvah for the blood redeemer to kill him.
Despite the statement in the text, the Rambam does not consider the redemption of the blood to be one of the 613 mitzvot of the Torah, but rather apparently includes this in the mitzvah to execute by decapitation. Significantly, the Ramban (in his Hosafot to Sefer HaMitzvot) does include the blood redemption in his reckoning of the 613 mitzvot.

See the notes on Halachah 5 and Chapter 5. Halachah 7, from which it appears that the blood redeemer should not kill the murderer until he is convicted by the court.

I.e., his descendants or his paternal relatives.

E. g., a convert who did not father any Jewish children.

Although a grandson is obligated to show certain tokens of respect to his grandfather, this obligation is superseded by the commandment to redeem his father’s blood.

For the commandment to redeem the blood of one’s brother does not supersede the commandment to honor one’s father.

For this is a positive commandment not dependent on a specific time, and thus it is incumbent on both men and women (Merkevet HaMishneh).

Sefer HaMitzvot (Negative Commandment 296) and Sefer HaChinuch (Mitzvah 412) regard this as one of the Torah’s 613 commandments. Significantly, in his Sefer HaMitzvot, the Rambam does not mention that this mitzvah is incumbent on the court, implying perhaps that it applies also to the blood redeemer.
The rationale for this mitzvah is obvious. If a person were able to pay ransom for murdering, the rich would act wantonly and redeem any foul play with money (Sefer HaChinuch, loc. cit.).

See the Guide for the Perplexed, Volume III, Chapter 41, which states that even if the victim did not die immediately and forgave the murderer, it is still a mitzvah to execute him.

See Sefer HaMitzvot, General Principle 5, which explains that this is not considered one of the 613 mitzvot, for it does not involve a specific deed.

On this verse, the Sifre comments that murder makes the land impure, drives the Divine Presence from the land and causes the destruction of the Temple.

Nor by the blood redeemer.

Sefer HaMitzvot (Negative Commandment 292) and Sefer HaChinuch (Mitzvah 409) regard this as one of the Torah’s 613 commandments. The rationale is to protect the rights of every criminal and give him the opportunity for due process of the law.
In Sefer HaMitzvot, the Rambam quotes the Sifre Zuta, which states that even if a person killed a colleague in the presence of a court of law, the court may not execute him until he is tried by another court.

Who is not liable for execution by the court.

Sefer HaMitzvot (Positive Commandment 247) and Sefer HaChinuch (Mitzvah 600) regard this as one of the Torah’s 613 commandments.

As explained in the following halachah, it is, nevertheless, desirable not to kill the pursuer, if possible.

The person pursuing his colleague with the intent to murder.

Sanhedrin 72b states that it is not necessary to give a rodef a warning, as is required with regard to a person executed by the court. From the Rambam’s words, however, it appears that he considers it desirable to offer a warning, but that one should not hesitate and wait to see that it is accepted, because the intended victim’s life is at stake. Sefer Me’irat Einayim 425:3 states that, after the fact, even if no warning whatsoever is given, one may kill the rodef to save his intended victim.

Sefer HaMitzvot, loc. cit. considers this to be the proof-text that illustrates this commandment. I.e., the woman is considered a rodef because she is attacking her husband’s antagonist in a way that can kill him.

The rodef should be maimed in a way that prevents him from carrying out his intent.

Sefer HaMitzvot (Negative Commandment 293) and Sefer HaChinuch (Mitzvah 601) regard this as one of the Torah’s 613 commandments.
The rationale is that taking pity on the rodef’s life will enable him to perform harm. This provides us with an important lesson: mercy and kindness are important emotions, but they must be controlled by the Torah’s guidelines. Otherwise, by showing mercy to the cruel, one will eventually be cruel to the merciful (see Kohelet Rabbah 7:37).

Oholot 7:6.

And remove it limb by limb (Ibid.).

Thus, since the fetus is endangering its mother’s life, it may be killed. The life of the mother is given priority over the life of the fetus.
Rabbi Akiva Eiger notes that the rationale for this priority is that the fetus is not considered to be “a soul,” a living being in the complete sense. He therefore asks why the principle of rodef applies? Even without that principle, it should be obvious that one may abort the fetus. Moreover, once the head emerges, the fetus is considered “a soul.” Nevertheless, even though it is still “pursuing” its mother, it is not touched.
(In this context, see also Hilchot Melachim 9:4, which states that a gentile who kills a fetus is liable for murder.)

But the body remains stuck in the birth canal.

See Pitchei Teshuvah 425:2, which mentions opinions that maintain that when it is certain that both the mother and the fetus will die if the fetus is not aborted, an abortion is permitted.

Raping a consecrated maiden is considered to be adultery and is punishable by death. Therefore, one is allowed to kill the pursuer. If, however, a person seeks to rape a maiden who has not been consecrated, efforts should be made to prevent this, but the would-be rapist may not be killed.

Although the verse mentions only a consecrated maiden, our Sages understood it as applying to all arayot - i.e., women with whom sexual relations are forbidden and punishable by execution or karet
The term arayot refers to adulterous or incestuous sexual relations. It also includes relations with a niddah, a woman who is ritually impure because of menstrual bleeding. Note, however, the gloss of Rabbi Akiva Eiger, who maintains that the laws of rodef do not apply with regard to relations with a niddah..

Sexual relations with an animal are also considered one of the arayot and are punishable by execution. Nevertheless, since it does not bring shame to a human victim, it is considered to be a sin between man and God - like idol worship or the desecration of the Sabbath - and one may not kill the person seeking to commit the transgression.

Because the transgression does not involve another person.
Sanhedrin 73b mentions Sages who maintain that one may kill a person before he commits these transgressions, but the majority follow the ruling cited by the Rambam. The difference is that the minority opinion gives priority to the concept that killing the person seeking to perform the transgression is a spiritual benefit for him, for he will die without having committed the transgressions. The other view maintains that, since no other person is involved, we should allow the person to exercise free choice, however wrong his choice may be.
Note the Rambam’s Commentary on the Mishnah (Sanhedrin 8:7), which states that although one may not kill a person who seeks to perform these transgressions, one should try to prevent him by all other means.

Our translation is based on Sanhedrin 73b.
Once the head of the male organ has been inserted into the vaginal canal, the transgression has been committed. As such, Jewish law does not recognize an advantage to killing the rapist on the spot, and requires that he be tried in court.

Sanhedrin, ibid., defines the term “concluded sexual relations” as having inserting the entire organ, not as ejaculation.

Where he will be tried for his crime.
The license to kill a rodef is granted only to prevent a transgression. Since the transgression was already committed, no one has the right to take the law into his hands. The matter must be handled by the court (Kessef Mishneh).

The license to kill is not granted by her, but by the Torah. And it is the Torah’s laws that must be heeded. If, however, the woman’s life is actually in danger, the pursuers should allow the transgression to be committed rather than cause her death.
Note Sefer Me’irat Einayim 425:12, which discusses whether the rodef may be killed in a situation where the woman consents to the transgression.

Halachah 7.

I.e., he will suffer death at God’s hands (Kessef Mishneh).
The Bayit Chadash (Choshen Mishpat 425) explains that the person who killed the rodef may be slain by the redeemer of the rodef’s blood. Indeed, he cites Sanhedrin 49a, which explains that Yoav slew Avner (II Samuel 3:27) for this reason. Avner had slain Yoav’s brother Asah’el because he had pursued him (Ibid. 2:23). Nevertheless, Yoav still held Avner liable, because he could have saved himself by maiming Asah’el and not killing him.

The Tur (Choshen Mishpat 425) differs with the Rambam, asking why if the person who killed the rodef is liable to die, may he not be executed. The Kessef Mishneh defends the Rambam’s ruling, explaining that the killer cannot be executed by a court, since his intent is to save the intended victim, and it is not possible to give him a proper warning.

This commandment applies to the laws of a rodef mentioned in the previous halachot, but also to other situations, as the Rambam proceeds to explain.

Sefer HaMitzvot (Negative Commandment 297) and Sefer HaChinuch (Mitzvah 237) regard this as one of the Torah’s 613 commandments.

The Kessef Mishneh cites the Jerusalem Talmud, which mentions that even when a person must endanger his own life to endeavor to save his colleague, he is obligated to do so. See Sefer Me’irat Einayim 426:2.

Needless to say, the person whose life was saved must afterwards reimburse the person who saved it for the expenses he undertook (Kessef Mishneh).

This instance demonstrates that the mitzvah applies even when, as in the example the Rambam employs, the danger - though imminent - is not yet a factor of the immediate present.

See Halachah 7.

See Halachah 8.

See the previous halachah.

As stated in Hilchot Sanhedrin 18:2, lashes are given as punishment for the violation of a prohibition only when an actual deed is involved.