What major decision did Arizona v. Gant deliver regarding vehicle searches post-arrest?

The decision in Arizona v. Gant established that searches of a vehicle following an arrest are permissible only if the arrestee is within reaching distance of the vehicle at the time of the search. This ruling built upon the precedent set by Chimel v. California, which permits the search of an arrestee's immediate area for weapons or evidence that could be destroyed.

In Gant's case, the Supreme Court emphasized that the need for officer safety and the preservation of evidence is only justified when the suspect could access the vehicle at the time of the search. If the arrestee has been secured and removed from the vicinity of the vehicle, law enforcement does not have the same level of justification to conduct a search. Consequently, this decision limits the scope of vehicle searches after an arrest, reinforcing the need for a reasonable connection between the arrestee and the area to be searched, thereby protecting Fourth Amendment rights.