Identify the primary legal source that governs arrest procedures.

The Fourth Amendment of the U.S. Constitution is the primary legal source that governs arrest procedures because it protects individuals against unreasonable searches and seizures. It establishes the need for law enforcement to have probable cause or a warrant based on probable cause before making an arrest. This ensures that individuals are not subjected to arbitrary or unjustified intrusions upon their privacy or freedom by government authorities.

In the context of arrest procedures, the Fourth Amendment creates a framework within which officers must operate, requiring them to adhere to constitutional standards that balance the need for effective law enforcement with individual rights. The Fourth Amendment is fundamental in delineating when and how police can legally detain a person, ensuring that any arrest is supported by sufficient justification. Thus, it provides the legal foundation for understanding the conditions and limitations under which arrests can be made.