How does the state prove that you were under the influence of drugs?

In New Mexico, they have to prove that you were under the influence such that you were incapable of safely operating a motor vehicle. They can prove that through driving and also by performing the Standard Field Sobriety Test. On drug cases, they use another battery of tests that are run by a “Drug Recognition Expert,” a specially trained officer to check if somebody is under the influence of drugs, and they can use the results of those tests against you as well to show intoxication.