Final answer:
If Mary has been arrested for driving under the influence of drugs, the police may have the authority to search her vehicle.
Step-by-step explanation:
In general, if a person has been arrested for driving under the influence of drugs, the police may have the authority to search their vehicle. This is because when a person is lawfully arrested, the police can conduct a search of the area within their immediate control, which includes the passenger compartment of their vehicle. However, it's important to note that the specific laws regarding vehicle searches can vary depending on the jurisdiction and the circumstances of the arrest.