Beyond the dietary laws that govern what enters the body, the Biblical text introduces another layer of physical and spiritual boundary: the impurity transferred through touch. While consuming forbidden foods causes an internal spiritual blemish, touching an animal carcass creates a symbolic state of impurity that temporarily prevents a person from interacting with sacred items or entering the Temple [רש ר הירש, רד צ הופמן, ביאור יש״ר]. This impurity is rooted directly in the concepts of cessation and death. Because it is the state of death that generates this impurity, an animal that is properly slaughtered does not make a person impure; the law applies only to creatures that die on their own [רמב״ן, הטור הארוך, רקנאטי]. The primary approach among commentators is that this rule targets domestic and wild animals, specifically excluding creatures like fish, birds, and grasshoppers, whose carcasses do not transfer impurity through touch. A minority view, however, suggests the rule actually points back to the flying, swarming creatures mentioned previously [אבן עזרא].
A subtle connection in the text links this rule back to the dietary laws, establishing that the minimum amount of a carcass required to transfer impurity through touch is the same as the minimum amount required to violate the eating prohibition, which is the volume of an olive [אור החיים]. Furthermore, becoming impure is not presented as a command or an obligation. It is simply a statement of cause and effect: contact results in impurity [רש״י, מזרחי, שפתי חכמים, גור אריה]. Yet, this phrasing also implies a degree of permission. Unlike the strict prohibition against eating forbidden animals, a person is allowed to intentionally touch a carcass and become impure if they choose, provided they undergo the proper purification process afterward [בכור שור, הדר זקנים].
The transfer of impurity through contact operates under specific physical conditions. It requires direct contact with the external surface of the dead animal, rather than its internal organs [רד צ הופמן]. Because the touch must be direct, an unbroken bone containing marrow does not transfer impurity unless it is punctured [תורה תמימה]. Additionally, the definition of a carcass extends beyond a complete dead body. It includes any limb torn from either a living or a dead animal, as a detached limb is treated as lifeless matter [אור החיים, תורה תמימה, מלבי״ם, ברטנורא].
The process of purification requires a person to wait until evening, but the passage of time alone is not enough to restore purity. Relying on the broader context of purification laws, commentators agree that a person must fully immerse and wash their body in water. Only after this immersion, once the sun sets in the evening, is the state of impurity finally lifted [רמב״ן, הטור הארוך, אבן עזרא, רלב״ג]. This cleansing process carries deep symbolic meaning. The purifying water represents God's supreme attribute of kindness, which washes away the impurity naturally associated with His attribute of strict justice [רקנאטי].