The Church has acknowledged that the laity are not required by divine law to receive Communion under both or either species at Mass, any priest who is celebrating Mass is required by divine law to do both.
What happens is that the priest commits a grave violation of liturgical and divine law. I was at a mass where when it came time for the priest to take communion, he told us that he could not because he had to fast for a medical procedure the following day. What happens when a priest does not consume the body and blood of Christ at Mass.
