Any offense committed prior to the effective date of this title shall be governed by the ordinances of this municipality existing at the time of commission thereof, except that a defense or limitation on punishment available under this title shall be available to any defendant tried or retried after the effective date. An offense under this title shall be deemed to have been committed prior to the effective date of this title if any of the elements of the offense occurred prior to the effective date. (Code 1975 § 1-111(B))