Marijuana DUI or driving under the influence charges are just as significant as driving when drinking, although testing for marijuana is done by urine or blood tests rather than by a roadside breathalyzer. This in itself can cause a problem since THC, the metabolized form of marijuana, can stay in the bloodstream for up to 30 days after consumption. In addition there is currently no universally accepted level of THC that is considered to have an impact or cause a person to be impaired in a legal sense. In most cases where individuals are charged with marijuana DUI there is also some type of alcohol noted by the officer, and in many cases other types of controlled substances have either been used or are present in the vehicle, making multiple charges including possession issues a very real possibility. As with DUI charges for alcohol, individual drivers that refuse to participate in a field sobriety test of a blood or urine test as requested by law enforcement will face additional serious charges, regardless of the results of the test.