There are a variety of tests that officers may use on the side of the road or elsewhere to establish the presence of substances and impairment.
For Boating Under the Influence cases, there are some special adaptations of field tests and tests that would not otherwise be considered reliable enough.
For Driving Under the Influence cases, the initial battery that most people face is Standardized Field Sobriety Evaluations. They may also face tests pulled from Advanced Roadside Impaired Driving Evaluation (ARIDE) and Drug Recognition Evaluation (DRE) training programs. Anything else is considered non-standard and there is likely a strong argument that such testing should not come into evidence.
In addition, there are a variety of active and passive alcohol sensors on the market and available to officers for screening. Some companies are working to develop marijuana passive and active screening devices. In Georgia, a handheld alcohol screening test may be used and testified to, but such testimony cannot include the numerical result displayed.