What exactly does “implied consent” mean? In the Fourth Amendment area, consent—unmodified—means that a person has agreed to allow the police to do something that they might otherwise need a warrant or probable cause or some other justification to do. For example, say police pull you over for speeding while you are driving down the highway, and they then ask whether you mind if they search your car. A response of “not at all, officer; go right ahead” constitutes consent to the search of your vehicle. Without your permission, the Fourth Amendment would bar the vehicle search absent probable cause or some exception to the probable cause requirement. The theory behind consent is that if you say police may search or seize or do something else that they ordinarily may not do, then police act reasonably when they act on that consent. Consent searches and seizures are efficient, because they spare the police the need to jump through procedural hoops.
Here is the case that is referred to in the article: Mitchell v Wisconsin