Nevada law requires a police officer to make an arrest, “unless mitigating circumstances exist,” where the police officer has probable cause to believe that that the person to be arrested has committed a domestic violence (battery) within the preceding 24 hours. This law requires police officers to make an arrest(s) during domestic violence investigations, even where the victim is resistant to the aggressor’s arrest and/or the situation has quieted. In fact, even where the police officer has probable cause to believe that a “mutual battery” has occurred, the police officer is required to attempt to determine which person was the “primary physical aggressor” and make an arrest of that person. Once arrested, the person arrested cannot be released or admitted to bail until he or she has been incarcerated for at least 12 hours. This 12 hour hold is commonly referred to as the “cool down period.”