Testing Options (Court)
Generally, there are 3 matrices we can work with - hair, urine, and oral fluid
Oral Fluid
The shortest of all detection windows. Some substances (such as benzodiazepines) clear oral fluid within 2 - 4 hours, with most clearing within 8 hours, of being used meaning that detection is a likely sign of impairment. This has very little forensic application and all it would tell a court is 'drugs were not used in a short period prior to the test'
Urine
Urine testing is common for pre-employment medicals, probation, parole, or any testing where a person effectively needs proof you are not a drug addict. It shows approximately the last 4 days* of drug use and if done randomly, a few urine tests may be sufficient for a court, employer, parole board to determine drugs are not an issue for you.
*Metabolites of cannabis are notoriously lipophilic meaning, based on things like exercise and body fat composition - they may remain detectable for up to 12 months.
Hair Testing
Often called 'hair follicle testing' by the courts this test is the most comprehensive for determining issues. It typically will not reveal 'one off' drug use but will reveal a pattern of drug use over the past 42 to 180 days.