The following is not legal advice.
In general, Florida v. Royer says that only if there is a reasonable reason for doing so, a person may not be detained. For example:
The person approached, however, need not answer any question put to
him; indeed, he may decline to listen to the questions at all and may
go on his way. He may not be detained even momentarily without
reasonable, objective grounds for doing so; and his refusal to listen
or answer does not, without more, furnish those grounds. If there is
no detention - no seizure within the meaning of the Fourth Amendment -
then no constitutional rights have been infringed.
The question came up how DUI checkpoints are related to this because here people (in vehicles) are briefly detained.
Michigan Department of State Police v. Sitz (See also here) says that
- "Petitioner's highway sobriety checkpoint program is consistent with the Fourth Amendment." That is DUI check-points are legal. You are technically being detained for a short period of time. But, as you point out in your comment below, you don't have to submit to any test. The police at the stop will access you from the outside.
Delaware v. Prouse (see also here) was cited in Michigan Dep't of State Police v. Sitz and says that
Except where there is at least articulable and reasonable suspicion
that a motorist is unlicensed or that an automobile is not registered,
or that either the vehicle or an occupant is otherwise subject to
seizure for violation of law, stopping an automobile and detaining the
driver in order to check his driver's license and the registration of
the automobile are unreasonable under the Fourth Amendment.
Also, I find the following in Michigan Department of State Police v. Sitz referring to the Delaware v. Prouse it is stated that the Supreme Court
...went on to state that our holding did not cast doubt on the
permissibility of roadside truck weigh-stations and inspection
checkpoints, at which some vehicles may be subject to further
detention for safety and regulatory inspection than are others.
So, if there might be some "inspection points" where you can be subjected to "further detention".