4,043. The Eighteen Disqualifying Conditions

Hilchos Bias HaMikdash 9:14

If a person violated the law by building a temple (lower-case t) separate from the Temple (capital T) to sacrifice to God there, it is not considered an idolatrous temple. Nevertheless, a kohein who serves in such a temple may not serve in the Temple. Similarly, the service utensils of such a temple may not be used in the Temple; rather, they must be stored away. The Rambam opines that if a kohein who served in such a temple later serves in the Temple, his service is not invalidated.

Hilchos Bias HaMikdash 9:15

We have seen that eighteen things disqualify a person from performing the Temple service: (1) having served an idol; (2) being a non-kohein; (3) having a disqualifying blemish; (4) being uncircumcised; (5) being ritually unclean;(6) needing to wait for nightfall to complete purification; (7) needing to bring an offering to complete purification; (8) being in a state of bereavement; (9) being intoxicated; (10) lacking any of the kohanic garments; (11) wearing additional garments; (12) wearing torn garments; (13) having long hair; (14) failure to wash his hands and feet; (15) sitting; (16) having an interposition between his hand and the service vessel; (17) having an interposition between his foot and the ground; (18) serving with the left hand. One may not serve in any of these conditions and if one did so, their service is disqualified with the following exceptions: having long hair, having torn garments, and inadvertently slaughtering for an idol. If a kohein served in one of these conditions, the service is valid.