Before you read this post understand that NOTHING I SAY IS LEGAL ADVICE. Duh, Alex, that's the name of your blog. Well, it's worth repeating since I'm trying to explain some of your rights. I just want you to know that I'm only studying basic law and there are probably elements or exceptions that I don't know about, and I have to cover my own butt when relaying information relating to anything that could be considered close to a legal suggestion. The following is a hypothetical situation intended only for educational purposes. I do not intend to encourage you to break any law.
So you're driving along, maybe a little fast, with a fat sack of reefer in a backpack in your back seat, and an illegal British immigrant and a loaded machine gun in your trunk. I'm not really sure what you're doing, but that's none of my business. You get pulled over by a police officer because your blinker didn't blink when you changed lanes, a perfectly legitimate reason to stop you, but a pain in the ass nonetheless.
Don't freak out. Be polite and answer the officer's questions, but say no more. And if he asks to search your vehicle, you have a Constitutional right to decline. Unless of course, he has probable cause to search. Then you're at his mercy.
Generally, a police officer needs a warrant to search your property (I'll explain warrants another time). However, there a few exceptions. One of these relates to automobiles.
If a police officer has a probable cause, or PC, to believe that a vehicle contains fruits, instrumentalities or evidence of a crime, they may search the whole vehicle and any container that might REASONABLY contain the item for which they had probable cause to search.
What is probable cause? I'm glad you asked.
Probable cause requires trustworthy facts or knowledge sufficient for a reasonable person to believe that the suspect has committed or is committing a crime.
The officer approaches your window and asks you if you were aware that you didn't signal when you moved back to the right lane after passing a slow driver. Of course you signal, you always signal. I guess your light must be out.
Even though your eyes are clear and you show no sign of wrongdoing, the officer asks what you've been up to, if you have any contraband. You reply politely but sternly, "No sir."
The officer glances at your friend who seems a little nervous, isn't looking at the officer, and your passenger's eyes appear blitzed, red, squinted and hazy. Although the officer can't see your passenger's eyes clearly, he asks to search your car.
YOU CAN SAY NO. Just be polite. DON'T BE A SMARTASS and you can get your ticket and move on your way.
However, this comes to another warrant exception, consent. A warrantless search is valid if the police have a voluntary consent. I'm telling you this because knowledge of the right not to consent is not a prerequisite for voluntariness. IT DOESN'T MATTER WHETHER YOU KNOW YOU CAN REFUSE CONSENT OR NOT. If you consent to the search and he finds your gun, nugs, and human contraband, well you're going to jail.
Let it be noted that when consent is given, the consenter must have authority to do so.
Let's say your freaked out passenger tells the cop to go ahead and search. Well, if you don't object then the cop can go ahead and scour your vehicle for contraband.
Anyone with an apparent equal right to use or occupy the property may consent to a search, and evidence found may be used against the other owners or occupants. However, an occupant cannot give a valid consent to a search when a co-occupant is present and objects to the search and the search is directed against the co-occupant.
So, ASSERT YOUR RIGHTS. Politely decline. If the officer asks why, you can tell him you're in a hurry, you can tell him you know your rights, you can tell him any reason you can think of, but as I said before, DON'T BE A SMARTASS. He might imply that you're hiding something. He might straight up ask if you're hiding something, but you should know that your mere refusal to a search is not sufficient grounds for probable cause.
However, if your nervous friends spurts out something about the bag, the gun, or the Brit, then you're sunk. An admission like this is almost certainly sufficient to give a reasonable person the belief that your car contains contraband, so choose your friends wisely.
The scope of the search depends on what your passenger admits to. The officer can search in any container that could hold whatever contraband he reasonably believes you possess. If your passenger admits to the stowaway, then the officer can pretty much only search the trunk, or a portion of the car that could reasonably contain a human being. He could not search the backpack...yet.
However, once the officer finds the illegal immigrant you're going to jail, and he can search the entire car incident to arrest. Before you're secured and may still gain access to the car, the officer can make a protective sweep of the entire area of which you have control (to prevent you from pulling out a weapon and attacking him) which is pretty much the entire car. He can also search the entire passenger area if he reasonably believes that it contains evidence for the offense for which you are being arrested may be found there. I'm not sure if he would have reason to believe the passenger car contained evidence in this case.
After you, your passenger and the stowaway have been taken to jail your automobile will be impounded. At this point the police, if the department has a standard operating procedure, may search your ENTIRE VEHICLE, for inventory purposes (This is done to make sure you don't sue them for conversion, or taking your property. Nice of them, huh?) At this point they'll find the gun and the nugs too and there's nothing you can do about it. It doesn't matter at this point that they weren't looking for that specific contraband.
I hope the previous post has been informative. Lawyers, if I'm wrong, please enlighten us.