ורבי שמעון פוטר and Rabbi Shimon exempts him entirely.
ור"ש מה נפשך אי איסור חל על איסור ליחייב נמי משום גיד אי אין איסור חל על איסור ליחייב משום טומאה דקדים ואי אין בגידין בנותן טעם ליחייב משום גיד The Gemara objects: But according to Rabbi Shimon, whichever way you look at it, it is difficult. If a prohibition takes effect where another prohibition already exists, let Rabbi Shimon deem one liable for eating non-kosher meat and also due to the prohibition of eating the sciatic nerve. Conversely, if a prohibition does not take effect where another prohibition already exists, let Rabbi Shimon deem one liable due to the prohibition of eating meat from a non-kosher species, which preceded the prohibition of the sciatic nerve. And if Rabbi Shimon holds that sciatic nerves do not impart flavor, and therefore the prohibition of eating non-kosher meat does not apply, let him deem one liable due to the prohibition of eating the sciatic nerve.
אמר רבא לעולם קסבר אין בגידים בנותן טעם ושאני התם דאמר קרא (בראשית לב, לג) על כן לא יאכלו בני ישראל את גיד הנשה מי שגידו אסור ובשרו מותר יצתה זו שגידו אסור ובשרו אסור Rava said in response: Actually Rabbi Shimon holds that sciatic nerves do not impart flavor, and therefore they are not subject to the prohibition of eating non-kosher meat. And the reason the prohibition of eating the sciatic nerves does not apply to non-kosher animals is that it is different there, because the verse states: “Therefore the children of Israel eat not the sciatic nerve” (Genesis 32:33). This teaches that the prohibition applies only to a species whose sciatic nerve is forbidden but whose meat is permitted, and excludes this case of a non-kosher animal, whose sciatic nerve would be forbidden and whose meat would also be forbidden.
אמר רב יהודה אמר רב האוכל גיד הנשה של נבלה ר"מ מחייב שתים וחכמים אומרים אינו חייב אלא אחת § Having discussed the status of the sciatic nerve of a non-kosher animal, the Gemara addresses the status of the sciatic nerve of a kosher animal that did not undergo a proper ritual slaughter. Rav Yehuda says that Rav says: With regard to one who eats the sciatic nerve of an unslaughtered carcass, Rabbi Meir deems him liable to receive two sets of lashes, and the Rabbis say: He is liable to receive only one set of lashes.
ומודים חכמים לר"מ באוכל גיד הנשה של עולה ושל שור הנסקל שחייב שתים And the Rabbis concede to Rabbi Meir in a case where one eats the sciatic nerve of a burnt offering or of an ox that is stoned that he is liable to receive two sets of lashes. The prohibitions concerning a burnt offering and an ox that is stoned are more severe than that of the sciatic nerve, in that it is forbidden to derive any benefit from them, whereas the sciatic nerve is merely forbidden for consumption. Consequently, these prohibitions take effect even with regard to the sciatic nerve, despite the fact that the sciatic nerve was already forbidden before the animal was consecrated or before it gored a person and became liable to be stoned.
ומאן האי תנא דבאיסור כולל איסור חל על איסור לית ליה איסור כולל באיסור חמור אית ליה The Gemara challenges: And who is this tanna who does not hold that in the case of a more inclusive prohibition, the prohibition takes effect where another prohibition already exists, and consequently, according to his opinion the prohibition of eating an unslaughtered animal, which applies to the entire animal, does not take effect with regard to the sciatic nerve. Yet, he does hold that where the second prohibition is both a more inclusive prohibition and a more stringent prohibition, it does take effect, and therefore the prohibition of eating a burnt offering or an ox that is stoned does take effect with regard to the sciatic nerve.
אמר רבא רבי יוסי הגלילי היא דתנן טמא שאכל קדש בין קדש טמא בין קדש טהור חייב Rava said: It is Rabbi Yosei HaGelili who holds that a more inclusive prohibition does not take effect where there is an already existing prohibition. As we learned in a mishna (Zevaḥim 106a): One who is ritually impure who ate sacrificial food, whether it was ritually impure sacrificial food or ritually pure sacrificial food, is liable to receive karet if he did so intentionally and to bring a sliding-scale offering if he did so unwittingly.
רבי יוסי הגלילי אומר טמא שאכל את הטהור חייב טמא שאכל את הטמא פטור שלא אכל אלא דבר טמא Rabbi Yosei HaGelili says: An impure individual who ate pure sacrificial food is liable. But an impure individual who ate impure sacrificial food is exempt, as he merely ate an impure item, and the prohibition of eating sacrificial food while one is impure does not apply to impure sacrificial food.
אמרו לו אף טמא שאכל את הטהור כיון שנגע בו טמאהו The Rabbis said to him: According to your logic, this halakha would apply even in a case of an impure individual who ate what had been pure sacrificial food, because once he has touched it, he has thereby rendered it impure. Yet, in such a case, he is certainly liable for eating it. So too, an impure individual who ate impure sacrificial food is liable.
שפיר קא אמרי ליה רבנן לר' יוסי הגלילי ואמר רבא בנטמא הגוף ואח"כ נטמא בשר כולי עלמא לא פליגי דחייב דאיסור כרת קדים The Gemara asks: The Rabbis are saying well to Rabbi Yosei HaGelili; why does Rabbi Yosei HaGelili disagree? And Rava said in elaboration of the dispute: In a case where the person’s body became impure and then afterward the sacrificial meat became impure, everyone agrees that he is liable if he eats the meat, as the prohibition of eating sacrificial meat while impure, which carries the punishment of karet, preceded the prohibition of eating impure sacrificial meat.
כי פליגי בנטמא בשר ואח"כ נטמא הגוף רבנן אית להו איסור כולל דמגו דמיחייב אחתיכות טהורות דעלמא מיחייב נמי אחתיכה טמאה They disagree when the meat became impure and then afterward the person’s body became impure. The Rabbis hold that a more inclusive prohibition takes effect even where there is an already existing prohibition. Consequently, since the prohibition for an impure person to eat sacrificial meat is more inclusive than the prohibition for a pure person to eat impure sacrificial meat, as an impure person is liable for eating even pure pieces of sacrificial meat that are permitted to the rest of the world, he is also liable for this prohibition when he eats an impure piece of sacrificial meat.
ורבי יוסי הגלילי לית ליה איסור כולל דמגו לא אמרינן And Rabbi Yosei HaGelili does not accept the principle that a more inclusive prohibition takes effect even where there is an already existing prohibition, as he holds that we do not say that since it applies to cases that were not yet prohibited it applies to all cases.
ורבי יוסי הגלילי נהי דאיסור כולל לית ליה באיסור קל יבא איסור חמור יחול על איסור קל ומאי ניהו טומאת הגוף שהרי טומאת הגוף בכרת The Gemara objects: But even according to Rabbi Yosei HaGelili, granted that he does not hold that a more inclusive prohibition always takes effect where there is an already existing prohibition. But in the case of an already existing lenient prohibition, a more stringent prohibition should come and take effect on the more lenient prohibition. And what is the more stringent prohibition? The prohibition due to the impurity of a person’s body, as one who eats sacrificial food when he has impurity of the body is liable to karet, whereas a pure person who eats impure sacrificial food is merely liable to be flogged. Consequently, the prohibition of eating sacrificial food while impure should apply even though the meat became impure before the person became impure.
אמר רב אשי מאן לימא לן דטומאת הגוף חמורה דלמא טומאת בשר חמורה דלית ליה טהרה במקוה Rav Ashi said: Who can say to us that the prohibition due to the impurity of a person’s body is more stringent? Perhaps the prohibition due to the impurity of the meat is more stringent, as impure meat does not have the possibility of restoring its state of purity via immersion in a ritual bath, whereas a ritually impure person can become pure in this manner.