Hi,my son was involved in an accident(not his fault). as he was sat in his mangled car dazed and cofused,some of his mates pulled up and one of them gave him a spliff to smoke to settle him down ( he can't remember if he smoked it in the car or outside). Anyway,the police turned up about an hour later and gave him a swab test which he naturally failed and took him off for a blood test( which will probably fail also). Do you think he has anything to worry about re driving ban etc ? His car and his person were searched and nothing found. Do the police have to prove (beyond reasonable doubt) that he was driving under the influence ?