CBP did not effectively target and examine rail shipments entering the United States from Mexico and Canada. Specifically, U.S. Customs and Border Protection Officers (CBPO) did not always target shipments using the mandatory Automated Targeting System (ATS) targeting criteria. CBPOs also did not always use the required radiation detection equipment to examine high-risk shipments. Finally, CBPOs did not always record the results of their rail cargo examinations in the Cargo Enforcement Reporting and Tracking System (CERTS). CBPOs were unaware of the correct targeting criteria or inadvertently used inappropriate criteria. In addition, one port did not have the required radiation detection equipment for its rail team, and CBPOs at two other ports used Personal Radiation Detectors to examine shipments. Rail CBPOs also received insufficient training on the use of ATS and CERTS. Finally, Supervisory CBPOs did not provide sufficient oversight to ensure CBPOs followed CBP policy. As a result, CBP may have failed to target or properly examine rail shipments that were at an increased risk to contain contraband or dangerous materials. In addition, CBP has no assurance that decisions to release these high-risk shipments into U.S. commerce were appropriate.