You do not have to have illegal substances directly on your person to be in danger of possession charges. If you are in a vehicle with another individual who does have drugs, police may arrest you. This applies even if you were previously unaware of the unlawful materials present in the automobile, particularly if no one confesses to owning them as this usually results in officers taking everyone into custody.
Constructive possession is a legal principle that holds you responsible for having drugs even if you are not guilty of actual possession. There are, however, certain things prosecutors must prove to convict you of this.
You had knowledge of the drugs
The court wants to prove that you knew they were in the vehicle with you and what they were even if you did not. The positive aspect is that this is rather difficult to do. Being near the illicit substances does not count as absolute proof — there must exist some other form of evidence, such as behavior or a statement that demonstrates your supposed knowledge. If no strong drug odor surrounds your person or the materials sat in a hidden space rather than in plain view, these circumstances make accusations harder to substantiate.
You had control over the drugs
This second criterion for guilt in a constructive possession case is easier to establish since all the prosecutor needs is to show that you had easy access to them. You fit this qualifier if the substances were within reach.
Since anything you say or do, including making hand gestures, may act against you in court, you may want to consider exercising your rights to remain silent and obtain legal aid. Cooperating and remaining polite may help minimize the amount of ammunition available to use against you.