First of all, in the military, a urinalysis is constitutional if it is based upon probable cause. Military Rule of Evidence 312 (d) and 315.
Rarely do we see cases involving hair samples, but the appellate courts have ruled that a positive urinalysis also provides probable for a hair sample. US v. Bethea, 61 M.J. 184 (C.A.A.F. 2004).
In cases where the test was conducted without probable cause, the exceptions to the probable cause requirement apply. There are lots of exceptions – good faith exception, exigent circumstances exceptions, etc.
Most positive urinalysis’ in the military is the result of “random” inspections. Military Rule of Evidence 313 (b) permits random inspections. Sometimes we can challenge the authority of the commander to order the inspection. Every now and then a civilian employee orders the inspection or some person other than the commander.
It’s not uncommon for subterfuge to be used in ordering a urinalysis. The classic example is the first sergeant who takes steps to initiate a urinalysis based on rumors. Under US v. Campbell, 41 M.J. 177 (C.M.A. 1994) that inspection probably will not hold up.
A urinalysis conducted for a valid medical purpose is also constitutional under Military Rule of Evidence 312 (f). Whether the medical purpose was valid or not may be an entirely different question.
In the Army – for example – regulations limit the uses of a medical urinalysis. AR 600-85, para. 10-13.
Generally, in all of the branches, limited use policies limit use of competence for duty tests and medical tests.
If drug use is discovered during a limited use test, the service member must receive an honorable discharge.
Where most people have confusion about test results is when it comes to administrative separations. Unfortunately, evidence obtained in violation of the constitution is admissible in an administrative separation or nonjudicial punishment unless it was obtained in bad faith (the testing officials knew it was unlawful).
If you have questions about the legality of a drug test, call a lawyer. We’re happy to help. There is lots of bad advice on the internet. People call us all the time with incorrect information and high hopes that their urinalysis results will be excluded from evidence.