A chemical test is a scientific medical examination of bodily fluids for the purpose of establishing the existence of illegal substances in or the blood alcohol content of an individual. A chemical test can be performed through the examination of blood, urine, or in some cases, the breath. If a person is pulled over when driving and is suspected of being intoxicated or under the influence of drugs, a chemical test is a normal step in establishing guilt. If a law enforcement officer requests that a person submit a chemical test, the individual is usually required to comply. If the person is not willing to take a chemical test at the scene of the event, then they will often be taken to a hospital to do so and will not be allowed to leave without submitting to the chemical test.
In most instances, a person who is asked by law enforcement to submit a chemical test is asked to do so when other implicating factors, such as slurred speech or driving erratically, are present. When a person fails a chemical test, they are found to be unable to drive. They are arrested on the scene for failing to comply with laws that forbid drunk and intoxicated persons to drive in a compromised condition.