Under what condition can a vehicle be searched incident to arrest?

A vehicle can be searched incident to arrest when the arrestee is unsecured and within reach of the vehicle because this embodies the rationale behind the exception to the warrant requirement. The key concern here is the safety of law enforcement officers and the preservation of evidence. When an arrestee is within reach of the passenger compartment of the vehicle, there is a potential risk that they could access weapons or destroy evidence related to the arrest. Therefore, law enforcement is justified in conducting a search of the vehicle to mitigate those risks.

The requirement that the arrestee is unsecured further emphasizes the immediacy of the threat; if the individual is handcuffed or secured, they pose a limited risk of accessing the vehicle's contents. This principle is rooted in ensuring officer safety and the proper administration of justice.

In this context, the other conditions mentioned in the alternative options do not align with the legal justifications necessary for a search incident to arrest.