Halacha

הלכה א
יִשְׂרָאֵל שֶׁאֵינוֹ יוֹדֵעַ חֲמִשָּׁה דְּבָרִים שֶׁמַּפְסִידִין אֶת הַשְּׁחִיטָה וְכַיּוֹצֵא בָּהֶן מֵהִלְכוֹת שְׁחִיטָה שֶׁבֵּאַרְנוּ וְשָׁחַט בֵּינוֹ לְבֵין עַצְמוֹ אָסוּר לֶאֱכל מִשְּׁחִיטָתוֹ. לֹא הוּא וְלֹא אֲחֵרִים. וַהֲרֵי זוֹ קְרוֹבָה לִסְפֵק נְבֵלָה וְהָאוֹכֵל מִמֶּנָּה כְּזַיִת מַכִּין אוֹתוֹ מַכַּת מַרְדּוּת:
כסף משנה
1.
When a Jew who does not know the five factors that disqualify ritual slaughter and the like concerning the laws of shechitah that we explained1The five factors mentioned in the previous chapter and how to prepare a knife [Kessef Mishneh; Rama (Yoreh De'ah 1:2)]. slaughters [an animal] in private,2If, however, a wise man supervises his actions, the slaughter is acceptable, as indicated by Halachah 5. The Maggid Mishneh quotes the Rashba as ruling that such a person may slaughter in the presence of a wise man even as an initial and preferred option. The Shulchan Aruch (Yoreh De'ah 1:3) accepts this ruling, but the Rama does not. it is forbidden for him and others to partake [of the animal that] he slaughtered. It is close to being considered a nevelah because of the doubt involved.3There is no factor that we see that would cause us to disqualify the slaughter. Nevertheless, since it is highly probable that he slaughtered the animal in a way that disqualified it and rendered it a nevelah, the animal is prohibited and placed in this category. When a person eats an olive-sized portion of its meat, he is worthy of stripes for rebellious conduct.

הלכה ב
וַאֲפִלּוּ שָׁחַט בְּפָנֵינוּ אַרְבַּע וְחָמֵשׁ פְּעָמִים שְׁחִיטָה כְּשֵׁרָה וַהֲרֵי שְׁחִיטָה זוֹ שֶׁשָּׁחַט בֵּינוֹ לְבֵין עַצְמוֹ שְׁחִיטָה נְכוֹנָה וּגְמוּרָה אָסוּר לֶאֱכל מִמֶּנָּה. הוֹאִיל וְאֵינוֹ יוֹדֵעַ דְּבָרִים הַמַּפְסִידִים אֶפְשָׁר שֶׁיַּפְסִיד הַשְּׁחִיטָה וְהוּא אֵינוֹ יוֹדֵעַ כְּגוֹן שֶׁיִּשְׁהֶה אוֹ יִדְרֹס אוֹ יִשְׁחֹט בְּסַכִּין פְּגוּמָה וְכַיּוֹצֵא בְּאֵלּוּ בְּלֹא כַּוָּנָתוֹ:
כסף משנה
2.
Even if [such a person] slaughtered [animals] properly in our presence four or five times and this slaughter which he performed in private appears to be a proper and complete slaughter, it is forbidden to partake of it. Since he does not know the factors that can disqualify ritual slaughter, it is possible that he will cause the slaughter to be disqualified unknowingly.4Moreover, even if afterwards, he is taught the laws of ritual slaughter and states that he observed them when he slaughtered the animal, the ruling is not revised. Since he did not know the laws at that time, we fear that he did not observe them (Kessef Mishneh). For example, he may wait, apply pressure to the animal's neck and slit it, slaughter with a blemished knife, or the like inadvertently.

הלכה ג
יִשְׂרָאֵל שֶׁיּוֹדֵעַ הִלְכוֹת שְׁחִיטָה הֲרֵי זֶה לֹא יִשְׁחֹט בֵּינוֹ לְבֵין עַצְמוֹ לְכַתְּחִלָּה עַד שֶׁיִּשְׁחֹט בִּפְנֵי חָכָם פְּעָמִים רַבּוֹת עַד שֶׁיִּהְיֶה רָגִיל וְזָרִיז. וְאִם שָׁחַט תְּחִלָּה בֵּינוֹ לְבֵין עַצְמוֹ שְׁחִיטָתוֹ כְּשֵׁרָה:
כסף משנה
3.
[Even] when a Jew knows the laws of ritual slaughter, he should not slaughter in private as an initial and preferred option until he slaughters in the presence of a wise man many times until he is familiar and ardent.5This training process is still observed in the present age. Even though a person is familiar with the laws of ritual slaughter, he must first undergo apprenticeship under the guidance of a master and receive authorization to slaughter [Rama (Yoreh De'ah 1:1). If, however, at the outset, he slaughtered in private, his slaughter is acceptable.6I.e., after the fact, since he knows the laws, we do not disqualify the slaughter.

הלכה ד
הַיּוֹדֵעַ הִלְכוֹת שְׁחִיטָה וְשָׁחַט בִּפְנֵי חָכָם עַד שֶׁנַּעֲשָׂה רָגִיל הוּא הַנִּקְרָא מֻמְחֶה. וְכָל הַמֻּמְחִין שׁוֹחֲטִין לְכַתְּחִלָּה בֵּינָן לְבֵין עַצְמָן. וַאֲפִלּוּ נָשִׁים וַעֲבָדִים אִם הָיוּ מֻמְחִין הֲרֵי אֵלּוּ שׁוֹחֲטִין לְכַתְּחִלָּה:
כסף משנה
4.
When one knows the laws of ritual slaughter and slaughters in the presence of a wise man until he becomes familiar with ritual slaughter, he is called an expert. Any expert may slaughter in private as an initial and preferred option. Even women7The Rama (Yoreh De'ah 1:1) states that woman should not be allowed to slaughter as an initial and preferred option. and servants8This refers to Canaanite servants whose Halachic status is the same as women. The Tur (Yoreh De'ah 1) rules that in general servants may not serve as ritual slaughterers. See Siftei Cohen 1:2. may slaughter as an initial and preferred option.

הלכה ה
חֵרֵשׁ שׁוֹטֶה וְקָטָן וְשִׁכּוֹר שֶׁנִּתְבַּלְבְּלָה דַּעְתּוֹ שֶׁשָּׁחֲטוּ שְׁחִיטָתָן פְּסוּלָה מִפְּנֵי שֶׁאֵין בָּהֶן דַּעַת שֶׁמָּא יְקַלְקְלוּ. לְפִיכָךְ אִם שָׁחֲטוּ בִּפְנֵי הַיּוֹדֵעַ וְרָאָה אוֹתָן שֶׁשָּׁחֲטוּ כַּהֹגֶן שְׁחִיטָתָן כְּשֵׁרָה:
כסף משנה
5.
When a deaf-mute,9See Halachah 9 which grants a person with only one of these handicaps to slaughter. an intellectually or emotionally imbalanced person, a child,10The Shulchan Aruch (Yoreh De'ah 1:5) states that this refers to a child who does not know how to maneuver his hands for ritual slaughter. If he knows how to maneuver his hands he may be given an animal to slaughter at the outset. The Rama emphasizes that even so, the child may only slaughter in the presence of others. He may not slaughter alone. Furthermore, the Rama states that it is not customary for a person to receive authorization to slaughter until he is eighteen. The Siftei Cohen 1:25, however, rules more stringently. or a drunkard whose mind became befuddled11The Shulchan Aruch (Yoreh De'ah 1:8) states that one who becomes as drunk as Lot (see Genesis, ch. 19) may not slaughter. One who has not reached this stage of inebriation may slaughter at the outset. The Rama rules more stringently, stating that a person should never slaughter when drunk, for it is likely that he will disqualify the slaughter. slaughters, their slaughter is unacceptable. Since they do not have [adequate] mental control, we fear that they blundered. Therefore if they slaughtered in the presence of a knowledgeable person and he saw that they slaughtered properly, their slaughter is acceptable.

הלכה ו
מִי שֶׁאֵינוֹ יָדוּעַ אֶצְלֵנוּ שֶׁשָּׁחַט בֵּינוֹ לְבֵין עַצְמוֹ שׁוֹאֲלִין אוֹתוֹ. אִם נִמְצָא יוֹדֵעַ עִקְּרֵי הִלְכוֹת שְׁחִיטָה שְׁחִיטָתוֹ כְּשֵׁרָה:
כסף משנה
6.
When a person whose reputation12With regard to his proficiency in the laws of ritual slaughter. has not been established among us slaughters in private, we question him. If it is discovered that he knows the fundamental principles of ritual slaughter,13Those mentioned in the previous chapter and how to check a knife; there is no need for him to be knowledgeable with regard to all the particulars of the laws of ritual slaughter. his slaughter is acceptable.14The Kessef Mishneh explains that when there is no alternative (see the following halachah), we rely on the principle that most of those who slaughter are knowledgeable regarding its laws. Nevertheless, in this instance, since we have the opportunity to clarify the matter, we do so.

הלכה ז
הֲרֵי שֶׁרָאִינוּ יִשְׂרְאֵלִי מֵרָחוֹק שֶׁשָּׁחַט וְהָלַךְ לוֹ וְלֹא יָדַעְנוּ אִם יוֹדֵעַ אִם אֵינוֹ יוֹדֵעַ הֲרֵי זוֹ מֻתֶּרֶת. וְכֵן הָאוֹמֵר לִשְׁלוּחוֹ צֵא וּשְׁחֹט לִי וּמָצָא הַבְּהֵמָה שְׁחוּטָה וְאֵין יָדוּעַ אִם שְׁלוּחוֹ שְׁחָטָהּ אוֹ אַחֵר הֲרֵי זוֹ מֻתֶּרֶת. שֶׁרֹב הַמְּצוּיִין אֵצֶל שְׁחִיטָה מֻמְחִין הֵן:
כסף משנה
7.
When we saw from a distance that a Jew slaughtered [an animal] and departed and we do not know whether or not he knows the laws of ritual slaughter or not, [the animal] is permitted. Similarly, if a person tells his agent: "Go out and slaughter an animal on my behalf," and he finds a slaughtered animal, but does not know whether his agent or another person slaughtered it, [the animal] is permitted.15With regard to questions of business law, we rely on the presumption that an agent will perform the mission with which he was charged. We do not, however, accept this principle with regard to questions involving the Torah's prohibitions (Hilchot Terumot 4:6). Nevertheless, even if we know for certain that the agent did not slaughter the animal, we consider it as permitted because of the reason stated by the Rambam. [The rationale for both these laws is] that the majority of people who slaughter are expert.16And when there is no alternative we can rely on this presumption.
From the statements of the Rama (Yoreh De'ah 1:1), it appears that there is a slight difference between the present age and the Talmudic period. In the Talmudic era, most people were proficient in both the laws and practice of ritual slaughter. In the present age, this applies only to those who are occupied professionally in this field. Nevertheless, the laws remain the same, for we assume that only a person who is knowledgeable will actually slaughter animals.

הלכה ח
אָבַד לוֹ גְּדִי אוֹ תַּרְנְגוֹל וּמְצָאוֹ שָׁחוּט בַּבַּיִת מֻתָּר. שֶׁרֹב הַמְּצוּיִין אֵצֶל שְׁחִיטָה מֻמְחִים הֵן. מְצָאוֹ בַּשּׁוּק אָסוּר שֶׁמָּא נִתְנַבֵּל וּלְפִיכָךְ הֻשְׁלַךְ. וְכֵן אִם מְצָאוֹ בָּאַשְׁפָּה שֶׁבַּבַּיִת אָסוּר:
כסף משנה
8.
[The following rules apply when a person] loses a kid or a chicken. If he finds it slaughtered at home, it is permitted. [The rationale is that] the majority of people who slaughter are expert. If he finds it in the market place, it is forbidden; perhaps [it was slaughtered improperly and] became a nevelah and was therefore cast into the market place.17We are not speaking about a waste dump in the market place. In such an instance, all opinions would agree that the animal is forbidden. Instead, we are speaking about a situation where it was found in the marketplace at large. Chullin 12b records a dispute between two Sages concerning this matter and the Rambam chooses the more stringent ruling. Similarly, if he finds it on the waste dump at home, it is forbidden.18For the circumstances indicate that it was discarded.
As mentioned, there is a difference of opinion in the Talmud regarding this issue. Most Rishonim follow the more lenient view and rule that if the slaughtered animal is found in an ordinary place in the marketplace or in a waste dump at home, it is permitted. The Shulchan Aruch (Yoreh De'ah 1:4) also follows this view.

הלכה ט
מֻמְחֶה שֶׁנִּשְׁתַּתֵּק וַהֲרֵי הוּא מֵבִין וְשׁוֹמֵעַ וְדַעְתּוֹ נְכוֹנָה הֲרֵי זֶה שׁוֹחֵט לְכַתְּחִלָּה. וְכֵן מִי שֶׁאֵינוֹ שׁוֹמֵעַ הֲרֵי זֶה שׁוֹחֵט:
כסף משנה
9.
When an expert [slaughterer] loses his power of speech, but he is [still] capable of understanding, he can hear and he is of sound mind, he may slaughter as an initial and preferred option.19Another person should recite the blessing for him [Shulchan Aruch (Yoreh De'ah 1:7)]. Similarly, a person who does not hear,20As long as he has the ability to speak, he is not considered to be intellectually underdeveloped.
Rabbenu Asher explains that such a person should not slaughter as an initial and preferred option, because there is a difficulty with his recitation of the blessing. For a person must recite a blessing in a manner that enables him to hear it and that is impossible for such an individual. Indeed, the Jerusalem Talmud (Terumot 1:6) rules that a person who is dumb should not separate terumah at the outset for that reason [Maggid Mishneh; Shulchan Aruch (Yoreh De'ah 1:6)].
may slaughter.

הלכה י
הַסּוּמָא לֹא יִשְׁחֹט לְכַתְּחִלָּה אֶלָּא אִם כֵּן אֲחֵרִים רוֹאִים אוֹתוֹ וְאִם שָׁחַט שְׁחִיטָתוֹ כְּשֵׁרָה:
כסף משנה
10.
A blind man should not slaughter as an initial and preferred option unless others supervise him.21For we fear that he will err and not detect his error. The Siftei Cohen 1:35 quotes opinions that rule that a blind person should not slaughter even when others are watching him. If he slaughters, his slaughter is acceptable.22In this instance as well, the Siftei Cohen 1:36 mentions views that maintain that a person who was never able to see should not slaughter. Even after the fact, one should not partake of his slaughter.

הלכה יא
עַכּוּ''ם שֶׁשָּׁחַט אַף עַל פִּי שֶׁשָּׁחַט בִּפְנֵי יִשְׂרָאֵל בְּסַכִּין יָפָה וַאֲפִלּוּ הָיָה קָטָן שְׁחִיטָתוֹ נְבֵלָה וְלוֹקֶה עַל אֲכִילָתָהּ מִן הַתּוֹרָה. שֶׁנֶּאֱמַר (שמות לד טו) "וְקָרָא לְךָ וְאָכַלְתָּ מִזִּבְחוֹ". מֵאַחַר שֶׁהִזְהִיר שֶׁמָּא יֹאכַל מִזִּבְחוֹ אַתָּה לָמֵד שֶׁזִּבְחוֹ אָסוּר וְאֵינוֹ דּוֹמֶה לְיִשְׂרָאֵל שֶׁאֵינוֹ יוֹדֵעַ הִלְכוֹת שְׁחִיטָה:
כסף משנה
11.
When a gentile slaughters, even though he slaughters in the presence of a Jew, [using] a finely [honed] knife,23And is well-versed in the laws of ritual slaughter [the Rambam's Commentary to the Mishnah (Chullin 1:1)]. and even if he was a minor,24One might think that the slaughter of a minor has an advantage, because a minor's worship of idols is not significant. his slaughter is a nevelah. According to Scriptural Law, one is liable for lashes for partaking of it,25Thus a gentile's slaughter is not recognized by Scriptural Law. See, however, the following halachah.
In his Commentary to the Mishnah (ibid.), the Rambam explains that the reason the animal is forbidden is that, in general, when a gentile slaughters, his intent is that the animal is an offering to his false deity, it is, however, permissible to benefit from the animal. We do not consider it as a sacrifice to idols (Chullin 13b; see Chapter 2, Halachah 2), because we assume the gentile is not really sincere in his worship, he is merely mimicking his ancestors.
Rabbeinu Asher differs and explains that the Scriptural command for ritual slaughter states: "And you shall slaughter," implying that the slaughtering must be a Jew. Hence, a gentile is inherently disqualified; his thoughts are of no consequence. See the Siftei Cohen 2:2 and the Turei Zahav 2:1 who discuss this issue.
as [implied by Exodus 34:15]: "[Lest] he shall call you and you shall partake of his slaughter." Since the Torah warns lest one partake of his slaughter, you can infer that his slaughter is forbidden. He cannot be compared to a Jew who does not know the laws of ritual slaughter.

הלכה יב
וְגָדֵר גָּדוֹל גָּדְרוּ בַּדָּבָר שֶׁאֲפִלּוּ עַכּוּ''ם שֶׁאֵינוֹ עוֹבֵד עֲבוֹדָה זָרָה שְׁחִיטָתוֹ נְבֵלָה:
כסף משנה
12.
[Our Sages] established a great safeguard concerning this matter, [decreeing] that even [an animal] slaughtered by a gentile who does not serve false deities26E.g., a resident alien who accepts the Seven Universal Laws Commanded to Noah and his descendants (see Hilchot Issurei Bi'ah 14:7). is a nevelah.27According to the Rambam, if he does not serve false deities and knows the laws of ritual slaughter, his slaughter is acceptable according to Scriptural Law.
One might ask: If so, why is an animal slaughtered by a child a nevelah? A child is not liable for the service of false deities. The Lechem Mishneh answers that ultimately, the child will grow up and worship false deities.

הלכה יג
הִתְחִיל הָעַכּוּ''ם לִשְׁחֹט מִעוּט סִימָנִין וְגָמַר יִשְׂרָאֵל אוֹ הִתְחִיל יִשְׂרָאֵל וְגָמַר הָעַכּוּ''ם פְּסוּלָה. יֶשְׁנָהּ לִשְׁחִיטָתוֹ מִתְּחִלָּה וְעַד סוֹף. אֲבָל אִם שָׁחַט הָעַכּוּ''ם דָּבָר שֶׁאֵינוֹ עוֹשֶׂה אוֹתוֹ נְבֵלָה כְּגוֹן שֶׁשָּׁחַט חֲצִי הַגַּרְגֶּרֶת בִּלְבַד וְגָמַר יִשְׂרָאֵל הֲרֵי זוֹ כְּשֵׁרָה:
כסף משנה
13.
If a gentile began to slaughter and slit the minority of the signs and a Jew completed the slaughter or a Jew began the slaughter and a gentile completed it,28See the Siftei Cohen 2:27 maintains that if the Jew slit the majority of the gullet and windpipe, the slaughter is acceptable even if the gentile completed it. it is invalid.29Thus if a gentile slit the majority of the windpipe or any portion of the gullet, the slaughter is disqualified [Shulchan Aruch (Yoreh De'ah 2:10)]. [The rationale is that] slaughter [is considered an integral act, a single continuity] from the beginning to the end.30See Hilchot Pesulei HaMukdashim 1:18 for another application of this principle. If, however, a gentile slit [a portion of] an organ that does not cause the animal to be considered a nevelah, e.g., he slit half the windpipe and a Jew completed the slaughter, it is acceptable.31For, as stated in Chapter 1, Halachah 11, even if the windpipe is half slit because of other factors, it can be slaughtered acceptably.

הלכה יד
יִשְׂרָאֵל מוּמָר לַעֲבֵרָה מִן הָעֲבֵרוֹת שֶׁהָיָה מֻמְחֶה הֲרֵי זֶה שׁוֹחֵט לְכַתְּחִלָּה. וְצָרִיךְ יִשְׂרָאֵל כָּשֵׁר לִבְדֹּק אֶת הַסַּכִּין וְאַחַר כָּךְ יִתְּנֶנָּה לְמוּמָר זֶה לִשְׁחֹט בָּהּ מִפְּנֵי שֶׁחֶזְקָתוֹ שֶׁאֵינוֹ טוֹרֵחַ לִבְדֹּק. וְאִם הָיָה מוּמָר לַעֲבוֹדָה זָרָה אוֹ מְחַלֵּל שַׁבָּת בְּפַרְהֶסְיָא אוֹ אֶפִּיקוֹרוֹס וְהוּא הַכּוֹפֵר בַּתּוֹרָה וּבְמשֶׁה רַבֵּנוּ כְּמוֹ שֶׁבֵּאַרְנוּ בְּהִלְכוֹת תְּשׁוּבָה הֲרֵי הוּא כְּעַכּוּ''ם וּשְׁחִיטָתוֹ נְבֵלָה:
כסף משנה
14.
A Jew who is an apostate because of his transgression of a particular transgression32As the Rambam states in Hilchot Teshuvah 3:9, there is a concept of an apostate with regard to one transgression, i.e., "a person who has made a fixed practice of willfully violating a certain transgression [to the extent that] he is accustomed to transgressing and his deeds are public knowledge... provided he does so with the intent of angering God." who is an expert slaughterer may slaughter as an initial and preferred option.33Although he repeatedly violates that particular transgression, we do not assume that he will not slaughter correctly.
In his Kessef Mishneh, Rav Yosef Caro cites Chullin 4a which states that as long as if given a choice whether to eat kosher meat or non-kosher meat, the person would choose the kosher meat - even if he would partake of the non-kosher meat if kosher meat was not available - it is permitted to partake of an animal he slaughtered. The Kessef Mishneh continues, explaining that as long as one does not transgress with the intent of angering God, one may partake of an animal he slaughtered. In his Shulchan Aruch (Yoreh De'ah 2:5), he rules that an apostate who transgresses with the intent of angering God resembles a gentile and his slaughter is inherently unacceptable.
Kin'at Eliyahu notes that there is some difficulty with the Kessef Mishneh's interpretation, because Hilchot Teshuvah specifically states that a person is deemed an apostate only when his transgression is performed with the intent of angering God.
A Jew of acceptable repute must check the knife and afterwards give it to this apostate to slaughter with, for it can be presumed that he will not trouble himself to check [the knife].34Although we do not assume that he will definitely transgress, it is logical to presume that he will not be careful in his observance.
Although it also cites the Rambam's view, the Shulchan Aruch (Yoreh De'ah 2:6) mentions the opinion of the Tur and others who rule that if the person is not an apostate with regard to partaking of non-kosher meat, it is not even necessary to check his knife. He may slaughter in private. If, however, he is an apostate with regard to partaking of non-kosher meat, his knife must be checked. Moreover, if he shows no concern for kashrut at all, his slaughter is not acceptable [Rama (Yoreh De'ah 2:5].

If, by contrast, he was an apostate because of worship of false deities, one who violates the Sabbath in public,35See the conclusion of Hilchot Shabbat. or a heretic who denies the Torah and [the prophecy of] Moses our teacher, as we explained in Hilchot Teshuvah,36Hilchot Teshuvah 3:8. he is considered as a gentile and [an animal] he slaughters is a nevelah.

הלכה טו
מִי שֶׁהוּא פָּסוּל לְעֵדוּת בַּעֲבֵרָה מִן הָעֲבֵרוֹת שֶׁל תּוֹרָה הֲרֵי זֶה שׁוֹחֵט בֵּינוֹ לְבֵין עַצְמוֹ אִם הָיָה מֻמְחֶה. שֶׁאֵינוֹ מֵנִיחַ דָּבָר מֻתָּר וְאוֹכֵל דְּבַר אִסּוּר. שֶׁזּוֹ חֲזָקָה הִיא עַל כָּל יִשְׂרָאֵל וַאֲפִלּוּ הָרְשָׁעִים מֵהֶן:
כסף משנה
15.
[Even though] a person is disqualified as a witness because of his violation of a Scriptural prohibition,37See Hilchot Edut 10:1-3. he may [still] slaughter in private if he was an expert.38In this instance, the Rambam does not even require him to have another person observe him. Since his disregard for Jewish observance is not as severe as that of an apostate, he is allowed to slaughter on his own. For he would not leave something which is permitted and partake of something that is forbidden.39I.e., he would not slaughter the animal in an invalid way when it would be just as easy for him to slaughter it in an acceptable way. This is a presumption that applies with regard to all Jews, even those who are wicked.

הלכה טז
אֵלּוּ הַצְּדוֹקִין וְהַבַּיְתוֹסִין וְתַלְמִידֵיהֶן וְכָל הַטּוֹעִים אַחֲרֵיהֶן שֶׁאֵינָן מַאֲמִינִים בַּתּוֹרָה שֶׁבְּעַל פֶּה שְׁחִיטָתָן אֲסוּרָה. וְאִם שָׁחֲטוּ בְּפָנֵינוּ הֲרֵי זוֹ מֻתֶּרֶת. שֶׁאֵין אִסּוּר שְׁחִיטָתָן אֶלָּא שֶׁמָּא יְקַלְקְלוּ וְהֵם אֵינָן מַאֲמִינִין בְּתוֹרַת הַשְּׁחִיטָה לְפִיכָךְ אֵינָן נֶאֱמָנִין לוֹמַר לֹא קִלְקַלְנוּ:
כסף משנה
16.
These Tzadukkim, Beotosim, 40Tzadok and Beotus were two of the greatest students of Antigonus of Socho. As the Rambam states in his Commentary to the Mishnah (Avot 1:3), after they heard Antigonus teach: "Do not be as servants who serve their master for the sake of receiving a reward," they forsook Jewish practice, saying: "Is it just that we labor without receiving a reward?"
They began splinter sects with the intent of swaying the people after them. At first, they sought to abandon Jewish practice entirely. They saw, however, the people would not accept this and so they focused their complaints on the Oral Law, arguing that although the Written Law was of Divine origin, the Oral Law was not. Their intent, however, was to deny the entire Torah.
their disciples and all that err, following their path, who do not believe in the Oral Law - their slaughter is forbidden. If, however, they slaughtered [an animal] in our presence, it is permitted. For their slaughter is forbidden only because it is possible they blunder. Since they do not believe in the laws of ritual slaughter, we do not accept their word when they say, "We did not blunder."41The Rambam appears to be saying that there is no inherent difficulty with these individuals slaughtering an animal. The only question is whether or not they slaughtered correctly. Hence, when it is possible to verify that the slaughter was performed correctly, the animal is permitted. They are not placed in the same category as apostates. Kin'at Eliyahu adds that, based on the previous halachah, these Tzadukim must also be Sabbath observant.

הלכה יז
כְּשֶׁהָיוּ יִשְׂרָאֵל בַּמִּדְבָּר לֹא נִצְטַוּוּ בִּשְׁחִיטַת הַחֻלִּין אֶלָּא הָיוּ נוֹחֲרִין אוֹ שׁוֹחֲטִין וְאוֹכְלִין כִּשְׁאָר הָאֻמּוֹת. וְנִצְטַוּוּ בַּמִּדְבָּר שֶׁכָּל הָרוֹצֶה לִשְׁחֹט לֹא יִשְׁחֹט אֶלָּא שְׁלָמִים שֶׁנֶּאֱמַר (ויקרא יז ג) "אִישׁ אִישׁ מִבֵּית יִשְׂרָאֵל אֲשֶׁר יִשְׁחַט שׁוֹר" וְגוֹ' (ויקרא יז ד) "וְאֶל פֶּתַח אֹהֶל מוֹעֵד" וְגוֹ' (ויקרא יז ה) "לְמַעַן אֲשֶׁר יָבִיאוּ" וְגוֹ' (ויקרא יז ה) "וְזָבְחוּ זִבְחֵי שְׁלָמִים לַה'" וְגוֹ'. אֲבָל הָרוֹצֶה לִנְחֹר וְלֶאֱכל בַּמִּדְבָּר הָיָה נוֹחֵר:
כסף משנה
17.
When the Jews were journeying through the desert, they were not commanded to slaughter non-sacrificial animals.42There is a difference of opinion concerning this point among the Sages (Chullin 17a). The Rambam follows Rabbi Akiva's perspective. Instead, they would cut off their heads or slaughter them and eat as the other nations do. In the desert, they were commanded that everyone who desires to slaughter an animal [in the prescribed way] should slaughter only for the sake of a peace offering, as [Leviticus 17:3-5] states: "When a man from the house of Israel will slaughter an ox... and he will not bring it to the Tent of Meeting... [it will be considered as (spilled) blood]... so that the Children of Israel will bring their sacrifices... and slaughter these sacrifices as peace-offerings." If, however, a person desired to cut an animal's head off and partake [of the animal], in the desert, this was allowed.

הלכה יח
וּמִצְוָה זוֹ אֵינָהּ נוֹהֶגֶת לְדוֹרוֹת אֶלָּא בַּמִּדְבָּר בִּלְבַד בְּעֵת הֶתֵּר הַנְּחִירָה. וְנִצְטַוּוּ שָׁם שֶׁכְּשֶׁיִּכָּנְסוּ לָאָרֶץ תֵּאָסֵר הַנְּחִירָה וְלֹא יֹאכְלוּ חֻלִּין אֶלָּא בִּשְׁחִיטָה. וְיִשְׁחֲטוּ בְּכָל מָקוֹם לְעוֹלָם חוּץ לַעֲזָרָה שֶׁנֶּאֱמַר (דברים יב כ) "כִּי יַרְחִיב ה' אֱלֹהֶיךָ אֶת גְּבוּלְךָ" וְגוֹ' (דברים יב כא) "וְזָבַחְתָּ מִבְּקָרְךָ וּמִצֹּאנְךָ אֲשֶׁר נָתַן ה' אֱלֹהֶיךָ" וְגוֹ'. וְזוֹ הִיא הַמִּצְוָה הַנּוֹהֶגֶת לְדוֹרוֹת לִשְׁחֹט וְאַחַר כָּךְ יֵאָכֵל:
כסף משנה
18.
This mitzvah43The obligation to offer as a sacrifice an animal which one desires to ritually slaughter. is not observed forever, nor in the desert alone, at the time it was permitted to kill animals [and partake of them]. There they were commanded that when they would enter Eretz Yisrael, killing animals [for food] would be forbidden and ordinary animals could only be eaten after ritual slaughter. They would be allowed to slaughter in every place except the Temple Courtyard,44See Chapter 2, Halachah 1. as [Deuteronomy 12:20-21] states: "When God your Lord will expand your boundaries... and you shall slaughter from your cattle and your sheep which God your Lord gave you." This is the mitzvah to be observed for generations - to slaughter and then to eat.

קדושה הלכות שחיטה פרק ד
Kedushah Shechitah Chapter 4