Q: If during the Rite of Confirmation the celebrant (in this case a priest) forgets to use chrism, is the confirmation still valid?
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A: In his apostolic constitution on the sacrament of confirmation, Pope Paul VI wrote the following:
THE SACRAMENT OF CONFIRMATION IS CONFERRED THROUGH THE ANOINTING WITH CHRISM ON THE FOREHEAD, WHICH IS DONE BY THE LAYING ON OF THE HAND, AND THROUGH THE WORDS: ACCIPE SIGNACULUM DONI SPIRITUS SANCTI.
So, I’d say no, but for questions of validity, please ask a canon lawyer.