Those of us operate a vehicle on the road know it is illegal to do so while impaired from consuming too much alcohol. It is just as illegal to operate a vehicle while under the influence of drugs. If you are impaired under either you may be stopped and charged with DWI. 
Drugs such as LSD or cocaine can certainly lead to impairment, but so could legal substances such as cough medicine or prescription medicine. If you are impaired from excessive alcohol consumption police can test your breath to obtain your BAC to determine how intoxicated you are. The problem that arises from drug impairment is determining how impaired the driver is.
Additionally there are not guidelines as to how to determine exact legal impairment while under the influence of drugs. The law is exact that for alcohol the legal limit is .08 BAC, but there is not such a limit when it comes to drug intoxication.
In order to determine if someone is too impaired to driver while under the influence of drugs courts often rely on the police officer’s testimony. Law enforcement is trained on what signs and symptoms to look for, such as red/glassy eyes or sluggish physical responses. Some cases may present more obvious evidence of impairment but others can leave a more grey area open. The problem is that some individuals may present some of these symptoms but may only be fatigued, suffering from allergies, or another medical ailment that may lead an officer to believe a driver is impaired.
If you have been charged with DWI from drug it is important to hire an experienced attorney to defend you. This area of the law leaves open a lot of room for argument and an attorney who knows the law may be able to keep a DWI from appearing on your record forever.
