One of the difficulties for most people when interacting with the police is that of knowledge. If you were pulled over by the Missouri Highway Patrol during the Memorial Day weekend on suspicion of a DUI, that trooper is very likely far more experienced at their side of the interaction.
If they have been in the patrol for years, they may have participated in hundreds of traffic stops. They should understand the limits the Constitution places on their activities. They are also likely to have been schooled in how to get around those limits. You may only have a vague sense of what goes on during such an encounter and you may be stressed and fearful.
For instance, the type and extensiveness of the search they are permitted to perform during a traffic stop varies. If they stop you for driving 10 miles per hour over the speed limit or for weaving in and out of your lane, in most cases they cannot simply begin a wholesale search of your person, the interior of your car or the contents of your trunk.
Typically, they have to have “reasonable suspicion” of criminal activity beyond that of speeding or a DUI to search the vehicle. However, if they have a hunch that they might find something more interesting, they may ask if they could have a look around.
You do not have to consent to such a search. Sadly, some law enforcement officers may push the point or even lie on a police report, explaining they smelled marijuana or something else that would appear to justify their non-consensual search after the fact.
If they do find something, you may face drug or other criminal charges. If they don’t find anything, you may send you on your way with a ticket. No matter the outcome, you should always remain polite in your responses, but never say more than you must. If they do arrest you, you should immediately ask for an attorney and stop talking.
Silence is your friend and anything you do say, as the Miranda warning you have heard on TV a thousand times reminds you, can be used against you. So don’t talk and wait for your attorney.