I can only imagine what would happen if they just started stopping everyone on the freeway asking for ID...
Don't the police set up roadblocks which stop everybody if they're trying to apprehend a fugitive and they think said fugitive is driving in a particular direction?
There are a few reasons why police will set up roadblocks, yes, like a manhunt, missing prisoner, or DUI checkpoint. The big difference is they don't ask for ID at these positions, and I've never personally seen a roadblock on a major interstate, usually it is smaller roads and closer to where they think the person might be. Of course roadblocks are only useful if you can set up blocks all around a perimeter.
Also, those roadblocks are extremely temporary by nature, in terms of hours. Some of the border patrol checkpoints are basically permanent (a big sticking point in terms of the law).
Now let's expand this instead of fugitive, you're looking for illegal immigrants on a list of people. Does that mean you can stop everyone, and scan their ID to try to find these people? Not to mention search the vehicle?
In terms of the constitution, my right to free travel and the 4th amendment, I would hope that such a thing wouldn't happen, but it seems like that is what they are trying.
For airports, things are a bit different, and you waive certain rights because of public safety and the risk of terrorism. But I can see something like that being moved down to travel by road as well.
They definitely ask for ID at DUI roadblocks - license and registration, just like a traffic stop. They also will question passengers and if desired, ask you to go to 'secondary' for a search or K-9 inspection. I looked at the stats near San Bernardino while I was there for a time last year, and from what I recall they found more stolen vehicles, individuals with warrants and drugs than impaired drivers.
Yeah, that's part of the problem, they say the checkpoint is for one reason, but really they do it to try to catch anything going on.
For a DUI roadblock yeah they'll ask you for ID, but not all the people in the car. Also, for secondary at these border patrol checkpoints, I think it's pretty shaky legal ground, although they will try.
It honestly probably depends on circumstances you might not be aware of, like the description of the person they are looking for. Obviously if you match the description, then turn and run when you see them, they won't believe you're exercising. But if you don't match the description at all, I see that being a hard sell. I'd be asking the cop: do I match the description of the person you're looking for?
A DUI checkpoint is not an automatic waiver of your 4th amendment rights. In many places DUI checkpoints are not legal and instead they have drivers license checkpoints.
Don't the police set up roadblocks which stop everybody if they're trying to apprehend a fugitive and they think said fugitive is driving in a particular direction?