Leviticus 22:8

But of a dead carcase, or (that which hath been) killed (by violence), he may not eat to defile himself therewith. I am the Lord.

Certain brainless people have misinterpreted the verse in Ezekiel that reads “The kohanim shall not eat of anything that dies of itself, or is torn, whether it be bird or beast” [Ezekiel 44:31]. They claim that the prohibition applies only to food killed by birds or by beasts. This is nonsense. The Torah explicitly says, he must not eat an animal that died by itself, or an animal that was torn — i.e., any such animal. This verse teaches us that if he does eat such food, he may not officiate.

N’VEILAH’ (THAT WHICH DIETH OF ITSELF) ‘U’TREIFAH’ (OR IS TORN OF BEASTS) HE SHALL NOT EAT TO DEFILE HIMSELF THEREWITH. Scripture is stating that [the priest] should be careful not to eat n’veilah or treifah so that he should not become defiled therewith, and then it will be necessary for him to be separated from the holy things, and treifah, since the law applies to all Israelites (See Exodus 22:30 on treifah, and Deuteronomy 14:21 on n’veilah). Ramban’s explanation is that since the main theme of this section is to warn the priests to separate themselves from holy things when they are in a state of impurity, therefore the Torah mentions here the admonition against their eating n’veilah and treifah, since by so doing they will not only have transgressed a law which applies to all Israel, but they will also have to separate themselves from the Sanctuary and its holy things, as they will have been rendered impure. and he will not be able to eat of them until he bathes his flesh in water, and when the sun is down, he shall be clean. And the reason [why He mentioned here the prohibition against eating n’veilah and treifah], is that since He had referred to every sort of impurity which can occur to a person, seeing that He mentioned leprosy and an issue, which includes male and female, and the impurity of the dead, (Verse 5), this refers to the dead.” (Torath Kohanim, Emor 4:4). of semen, and of a swarming thing, therefore He goes back [in the verse before us] to warn [the priests to separate themselves] from the holy things when they are impure because of n’veiloth, and He warned them about this by way of an admonition against eating them. And the reason [why He singled out n’veilah and treifah in warning the priests not to eat them, and He did not mention those creeping things which also render the eater impure], is because a man’s soul finds it loathsome to eat creeping things, but it does not find n’veilah and treifah loathsome. Therefore He mentioned here [the prohibition against eating food which conveys] impurity in the case of [that food] which it is common [to eat]. Now the word treifah mentioned here [which renders the eater impure, must perforce] mean an animal that was torn by a lion or bear which killed it in the field, for when it is still alive [and is then slaughtered ritually] it does not convey impurity [although it …

נבלה וטרפה לא יאכל, even though they were permitted to eat the sacrificial birds without such procedure as slaughter, by simply snipping off, מליקה, their windpipe or food pipe.