No you don't have case. The police do not have to notify you prior to obtaining consent to search his car, or to put him through field sobriety test. You son should have never given up his right to search his car. He might be able to try and suppress the search since it appears he may have given consent under duress but that is probably a long shot. NEVER NEVER GIVE CONSENT TO SEARCH OR GIVE UP YOUR RIGHT TO REMAIN SILENT. Visit my blogs at djylaw.com on consent searches and right to remain silent.