Va. Code Ann. § 4.1-127

The regularity or legality of any referendum held pursuant to §§ 4.1-121, 4.1-123 and 4.1-124 shall be subject to the inquiry, determination, and judgment of the circuit court which ordered the referendum. The court shall proceed upon complaint of fifteen or more qualified voters of the county, city, or town, filed within thirty days after the date the results of the referendum are certified and setting out fully the grounds of contest. The complaint and the proceedings shall conform as nearly as practicable to the provisions of § 15.2-1654, and the judgment of the court entered of record shall be a final determination of the regularity and legality of the referendum.