The border fence could also be used to keep us in. Instead of building the fence, they are building checkpoints everywhere. The fourth amendment is going down hard and there was no reasonable suspicion for detainment once the valid drivers license was presented.
Now, around here, the cops would have grabbed the license out of my hand, and with all this talk of "Am I free to go" and "Am I being detained", would have landed me straight to the pavement, with no criminal record, and under arrest on some nonsense charge. That is how most cops operate.
What happened here is likely because:
there's a camera in the car.
you could tell the sheriff (or sergeant) concern that this woman was a federal agent.
there's a witness in the car.
the original officer was well trained not to escalate a conflict. he has not been turned into a police brutality robot.
Now, the cops have come to realize that even they are being recorded on their own patrol cars when they do a stop. And, now, with tools like Ustream, etc. even if a recording device if confiscated, the file can quickly be uploaded to YouTube before evidence is destroyed.
The law is clear on this matter about detainment and reasonable suspicion. There is no reasonable suspicion so there is no need for detainment. The sheriff, or sergeant, could not cite the specific statute, most likely because it does not exist or would never hold up in court. Even if arrested, the charges would be dropped once citizenship was presented to the judge.