Polite and non-aggressive is good. But, what if the officer insists on doing what you consider to be wrong or against your rights? Asserting one's rights at the wrong time and place can be very dangerous. This is true as one's "rights" are being redefined daily by the courts. So polite, non-aggressive and compliant is probably best.
The following is just some general advice to the members from an old, wore out copper with respect to citizen/officer contacts:
You can refuse, verbally, any search request. After voicing your objections it is then best to stand aside and watch the search being conducted. The legality will be worked out in court. Unless you constantly read court decisions you really only understand your rights as someone has explained them to you at some time in the past. Do not get into this type of discussion on the side of the road. Make your objections known, do not impede the officers and contact your attorney at the first possible moment should things go badly for you with regards to the search.
Lawful order? Depends on the circumstances at the time.
If you are driving a vehicle which matches a description the officer has of a vehicle used in a homicide, you'd best consider any order delivered at the point of a gun as lawful at that moment. Explanations will come later, just do as the officer tells you. No questions? No hesitation? You have absolutely no idea what information the officer has nor any idea why you have been stopped and are being ordered around. You think you were speeding and he/she suspects you of being a homicidal maniac with a decapitated body in the trunk. He/she may be just out of training and hyper as hell, scared shitless and barely in control, hoping that good ol' sarge will arrive in seconds. This is not the time to assert your "rights."
I often had to explain "rights" to people who understood them only as a teacher/professor, TV crime show, TV attorney, or "fully informed" private citizen interpreted them. Believe it or not, one's rights and civil liberties are in a constant state of flux. When I was a copper I was constantly being reminded of that fact through bulletins and in-service training.
A nationally known criminal defense attorney advised my brother's law class at Stanford to never argue criminal law with a police officer. The cop deals with it all the time and an attorney uses clerks to keep up and then only as the law applies to a case being handled at the time.
Now, all that said, there are cops and indeed departments that do not keep up. But, the court is the place to argue not the side of the road or at your front door. Things can generally only go south in those situations. Bite your tongue, watch closely, make notes and engage an attorney. The worst case scenario is you confronting a poorly trained cop with "John Wayne Syndrome". You can't win that confrontation, you should win in the courts if your position is correct and the officer didn't shoot you while being in fear for his safety.
Is a hand gun readily accessible in a locked glove box? Some jurisdictions yes, others no. Open bottle laws vary widely as to what constitutes a violation. Personal use marijuana? An ounce? Two cigarettes? When must you be read your "Miranda Rights?" When are you detained? Under suspicion? At what point are you under arrest? Can you be handcuffed if you are not under arrest and only being detained? Was the stop sign you ran legal? Who authorized it's placement? What's the definition of a public way or street? Lawful search? Unreasonable search?
A few years ago I knew the answer to all of those questions in my jurisdiction. Now? Not so much, as the rules change daily and I'm retired. On a rural road in . . . Indiana for example, I would never question an officer's instructions, even with my background and a badge in my pocket. Nothing good can come of such. When the situation is calm I might request the officer to summon his supervisor/commander or, if I feel aggrieved, I would see the officer in court.
