Law enforcement determines if someone is impaired through basic protocols, drug recognition experts, sobriety tests, and chemical tests. If they believe you are driving under the influence, they will require that you submit to a chemical test to determine the amount of THC per milliliter of blood or the presence of any metabolites. In those circumstances, you do not have the right to consult with a lawyer before taking the test, and your driver’s license could be suspended from 1 year up to 18 months if you refuse to take the chemical test to determine drugs present.