19 CFR §171.53

1. (a)Final administrative determination. Upon receipt of a petition filed pursuant to § 171.52, Customs shall determine first whether a final administrative determination of the case can be made within 21 days of the seizure. If such a final administrative determination is made within 21 days, no further action need be taken under this subpart.
2. (b)Determination within 20 days. If no such final administrative determination is made within 21 days of the seizure, Customs shall within 20 days after the receipt of the petition make a determination as follows:
   1. (1)If Customs determines that the factors listed in § 171.52(c) have been established, it shall terminate the administrative proceedings and release the property from seizure, or in the case of a commercial fishing industry vessel for which a summons has been issued, but not yet answered, dismiss the summons. The property shall not be returned if it is evidence of a violation of law.
   2. (2)If Customs determines that the factors listed in § 171.52(c) have not been established, it shall proceed with the administrative forfeiture.