GC, what you don't seem to understand that the Supreme Court considers Border Patrol checkpoints not on the border to be a very unique situation. Why? Because they stop everybody without any suspicion of wrongdoing. The courts have operated under the assumption that for a forced interaction by LEO to not be an "unreasonable seizure" under the Fourth Amendment, that the officer has to have some articulable suspicion for a crime having been committed. LEO cannot just pull people over willy nilly because they feel like it, since that would be an unreasonable seizure. Now in the case of Mimms, if LEO pulls over somebody for reasonable suspicion of a crime, they can order the person out of the car. But in the special case of suspicionless checkpoints, they cannot. I'm not sure why that point isn't coming across.
Border Patrol checkpoints are a special case, because they do not require suspicion of criminal activity to make persons stop. Now many think that these checkpoints are unconstitutional for that very reason. One being Justice Thomas of the SCOTUS,
"Indeed, I rather doubt that the Framers of the Fourth Amendment would have considered 'reasonable' a program of indiscriminate stops of individuals not suspected of wrongdoing."
- Justice Thomas [Dissenting] (City of Indianapolis vs Edmond), 2000
But he was in the minority, and in Fuertes the SCOTUS allowed the Border Patrol checkpoints but gave them very specific limitations. LIMITED. Brief. Immigration Status (not ordering people out of their vehicles).
"In United States v. Martinez-Fuerte the Supreme Court upheld the constitutionality of immigration checkpoints at which INS agents would stop travelers without suspicion for questioning about immigration status. The Court held that suspicionless 'stops for brief questioning routinely conducted at permanent checkpoints are consistent with the Fourth Amendment.' It explicitly limited its holding to stops and questioning to enforce the immigration laws; searches or 'further detention' must be based on consent or probable cause.'"
- Fifth Circuit (U.S. vs Machuca Barrera), 2001
"As we have stated, '[t]he Constitution [is] violated [ ] when the detention extend beyond the valid reason for the initial stop.'"
- Fifth Circuit (U.S. vs Machuca Barrera), 2001
"The scope of a stop is limited to investigation of matters justifying the stop."
- Fifth Circuit (U.S. vs Machuca Barrera), 2001
"The Fourth Amendment's requirement that stops be reasonable applies equally to a checkpoint."
- Fifth Circuit (U.S. vs Machuca Barrera), 2001
"We have already noted that the permissible duration of the stop is limited to the time reasonably necessary to complete a brief investigation of the matter within the scope of the stop. The scope of an immigration checkpoint stop is limited to the justifying, programmatic purpose of the stop: determining the citizenship status of persons passing through the checkpoint. The permissible duration of an immigration checkpoint stop is therefore the time reasonably necessary to determine the citizenship status of the persons stopped. This would include the time necessary to ascertain the number and identity of the occupants of the vehicle, inquire about citizenship status, request identification or other proof of citizenship, and request consent to extend the detention. The permissible duration of an immigration checkpoint stop is therefore brief. Indeed, the brevity of a valid immigration stop was a principal rationale for the Supreme Court's conclusion in Martinez-Fuerte that immigration checkpoints are constitutional: 'The stop does intrude to a limited extent on motorists' right to free passage without interruption ․ ut it involves only a brief detention of travelers during which [a]ll that is required of the vehicle's occupants is a response to a brief question or two and possibly the production of a document evidencing a right to be in the United States.' Within this brief window of time in which a Border Patrol agent may conduct a checkpoint stop, however, we will not scrutinize the particular questions a Border Patrol agent chooses to ask as long as in sum they generally relate to determining citizenship status."
- Fifth Circuit (U.S. vs Machuca Barrera), 2001
"...questioning unrelated to the justification for the stop that extends the duration of the stop violates the Fourth Amendment."
- Fifth Circuit (U.S. vs Machuca Barrera), 2001
And if questioning that is not related to inquiry into immigration status isn't allowed, then how on earth would making somebody exit their vehicle be allowed? Again, there is no suspicion for a crime here. If you are going to say that Mimms applies regardless of suspicion of a crime, then you might as well say that officers in a parking lot can order every driver out of their vehicle without cause for "officer safety" until they get into the Wal-Mart. It makes no sense, and it's not supported by the law.