I'm a retired lawyer with over 27 years of criminal law experience. I did other things too, but I always had a criminal case or two working in my office.
You don't have to be a student of constitutional law to understand how to deal with the police. The rules are very simple.
1. If you're stopped while driving, you have to give them your drivers license, registration, and insurance card. If you're legally carrying a firearm, it's a good idea to inform the officer and show your permit if one is required. If you're stopped as a pedestrian, know your State's law about showing ID. If it's not required in your State, refuse to show ID.
2. Do not talk to the officer about anything. Keep your mouth shut tight.
3. Do not consent to anything the officer suggests. Specifically say "No, not without a warrant." if an officer wants to look in your car, car trunk, briefcase, purse, or anywhere else under your control.
4. If you are at home or at your own workplace (where you are the owner or the boss) do not let the officers come inside without a warrant. Shut the door and refuse them admittance. Again just say "No, not without a warrant."
5. It's OK if they cuff you and take you in. By following rules 1 thru 4 you are in the best possible legal position. If you tried to talk and cooperate your way out of the encounter by ignoring rules 1 thru 4, you may have just sealed your own death warrant. Literally.
6. If you are not arrested, seek the advice of a criminal lawyer immediately if you think there is any possibility that the police may recontact you. If you are arrested, say absolutely nothing to the police until you have your lawyer present, and then let your lawyer do ALL the talking.
I know we all want to appear as nice guys, especially to the cops. But they are not our friends. They are in the business of sending people to prison, including death row. They would be perfectly happy to send you there next.
Remember, you have no idea why the officer stopped you. You may think you do, but you don't. Maybe someone matching your general description, or that of your car, just robbed a liquor store and killed a clerk a mile down the road you're on and in the direction from which you were coming. The officer is NOT going to tell you that. Also remember that everything you say to the officer, no matter how innocent it may seem to you at the time, can and will be used against you. And absolutely nothing you say to the officer is admissible to help you. So for God's sake, keep your damn trap shut.