Previous research has shown that cannabis can impair driving performance, although compared to alcohol the level of impairment is smaller. The combination of the two on the other hand can be very dangerous even when blood alcohol levels are below .05 per cent. For this reason, Governments have found it necessary to target the detection of impaired driving ability caused by drugs other than alcohol. Since a simplistic device such as a breath analysis instrument for the detection of alcohol, does not exist for the detection of cannabis, one possible tool for testing for impaired driving ability due to drugs, is the sobriety test. The sobriety test has been used for many years in the United States of America by the Los Angeles Police Department and has proven to be a successful tool in detecting drivers impaired by alcohol and drugs. This study aims to scientifically examine the efficiency of the sobriety test in detecting levels of cannabis intoxication and to examine whether any decrements in performance on the sobriety test is related to impaired driving ability. The study will do this by administering three different doses of cannabis (placebo, 1.78 per cent THC and 3.42 per cent THC) to 40 individuals (20 males, 20 female) and have them perform both the sobriety test and a driving simulator task. Blood and saliva samples will also be taken throughout the study to correlate performance on the tests, with levels of THC in the blood and saliva. Results of the study should be available by March 2000.