Which of the following is a key factor for determining the legality of a search warrant?

The key factor for determining the legality of a search warrant is particularly emphasized by the requirement of particularity. This principle ensures that the warrant specifies the exact place to be searched and the items to be seized. It is essential to limit the scope of the search to avoid violating Fourth Amendment rights against unreasonable searches. When a warrant lacks particularity, it can be deemed invalid, as it leaves too much discretion to law enforcement officers, which could lead to arbitrary or broad searches.

While probable cause is also crucial for obtaining a warrant, as it refers to the necessary level of belief that evidence of a crime will be found, it is the particularity requirement that directly influences the warrant's legality in terms of defining and constraining law enforcement's actions during the search. Relevance pertains to whether the evidence sought is pertinent to the investigation but does not address the specifics of where or what should be searched. The scope, while important in ensuring searches do not expand beyond what is authorized, is inherently tied to the particularity of the warrant's descriptions. Without a well-defined particularity, even a search conducted under probable cause may be rendered unlawful.