A DOJ Stop to the best of our understanding usually means that the Department of Justice (DOJ) has put out a traffic alert for law enforcement to stop a certain vehicle if seen.
For example when a child abduction has been announced and an Amber Alert is posted a DOJ stop may be in place for the vehicle of the person thought to have made the abduction. The National Center for Missing and Exploited Children (NCMEC) and the U.S. Department of Justice assumed responsibility for co-ordination at the national level for Amber Alerts.
When an elderly driver has gone missing it is labeled as a Silver Alert.
You can check with your state's Department of Motor Vehicles or local law enforcement to see if there are other definitions or meaning for a DOJ Stop.