Bechoros 5:4-5

Bechoros 5:4

If a firstborn animal was chasing someone so he kicked it, causing a blemish, he may slaughter the animal based on this blemish. Israelite shepherds are trusted regarding blemishes that are likely to be caused by humans but kohein shepherds are not trusted (because they have a motivation to injure the animal and then lie about it, since they will receive the animal). Rabban Shimon ben Gamliel says that a kohein shepherd is trusted about another person’s animal but not about his own. Rabbi Meir says that if a person is suspected in any matter, he may not judge or testify regarding that matter.

Bechoros 5:5

A kohein can be believed if he says that he showed the firstborn animal to an expert who determined that it was blemished. Everyone is trusted regarding blemishes of tithe animals. A firstborn animal that was blinded, whose front leg was cut off, or whose rear leg was broken, may be slaughtered on the say-so of three lay people; Rabbi Yosi says that even if there’s a court of 23 judges, a firstborn may not be slaughtered unless it has been evaluated by an expert.