Va. Code § 3.2-4913
The Commissioner shall report violations of this chapter to the attorney for the Commonwealth. It shall be the duty of every attorney for the Commonwealth, to whom the Commissioner shall report any violation of this chapter, to commence proceedings and prosecute without delay. This section shall not require the Commissioner to report, for the institution of prosecution under such sections, minor violations of this chapter if he believes the public interest will be adequately served in the circumstances by a suitable written notice of warning. In all prosecutions under this chapter involving the composition of an animal remedy, a certified copy of the official analysis signed by the analyst shall be accepted as prima facie evidence of the composition, provided the defendant has been furnished a copy thereof in advance of the trial.
Va. Code § 3.2-4913