The necessity for alcohol and drug screening arose from general substance abuse problems within society. Alcohol and drug screening has come to be necessary in a number of different ways, such as determining a person’s ability to hold a job, operate machinery and resist illegal substances. Alcohol and drug screens are used by employers, law enforcement officers and medical professionals, just to name a few.

Drug testing is not a new practice. For decades, people seeking employment in certain regions of North America have been aware that they must first pass a drug screen, and are aware that random drug screens could arise in their future. This practice was put into place for reasons of safety and liability. A person under the influence of a drug in the workplace can pose a danger to themselves and their co-workers, as well as becoming a liability to the organization they work for.

Drug screening is also used by law enforcement officers to determine if someone is illegally incapacitated, in the instance that an officer suspects someone is in possession of an illegal substance, or is over the legal limit of a substance while performing a certain activity. If someone has already been charged with one of these offences, often they will have to submit to repeated drug testing in the future.

Medical professionals will make use of drug screens in order to make a diagnosis on a patient, or to monitor a person’s sobriety, such as in the instance of a rehabilitation facility.
Alcohol screening is generally used for the same things drug screening is used for, but is a more recent practice, generally speaking. This is because alcohol consumption has long been legal in North America, so it is thought of as the lesser of two evils in many ways. For machinery operation, alcohol screening is a long-utilized practice, but for something like employment, it is very recent.