Charles Ellicott Commentary Leviticus 11:24

"And by these ye shall become unclean: whosoever toucheth the carcass of them shall be unclean until the even;" — Leviticus 11:24 (ASV)

And for these ye shall be unclean. —Rather, and by these you shall be defiled, that is, the beasts and animals specified in Leviticus 11:26-27.

Shall be unclean until the even. —For coming in contact with the dead body of the animals contracts defilement for the rest of the day, and until the beginning of a new day, which took place after sunset .

During these hours of legal uncleanness, he was not allowed to enter the sanctuary, touch any sacred thing, or interact with those who were legally clean. This was because contact with one who had contracted legal defilement imparted defilement to both persons and things.