The classic tests that doctors have used historically for screening for alcohol misuse namely the Gamma GT and MCV measurement are useless, being normal in 50% of subjects with alcohol used disorders. The DVLA have adopted measurement of carbohydrate deficient transferrin (CDT) in drivers who have lost their licence in the UK. CDT gives a time integrated index of alcohol consumption over the previous ten days or so, and has a specificity and sensitivity of 90% and 60%. In Germany they use measurement of urinary ethyl glucuronide/ethyl sulphate, which has a very high sensitivity (90%) and specificity (95%) and can detect alcohol consumption in the previous 72 hours.   There are other tests such as fatty acid ethyl esters, hair ethyl glucuronide which I can discuss with you. If you have lost your licence and need to prove continued abstinence from alcohol there are a number of approaches that I employ, including remote monitoring by breathalyser as well as CDT and urinary ethyl glucuronide testing.