Given the fact that attorneys for criminals identified by law enforcement, using facial recognition software platforms, will often seek to exclude the identification on a number of grounds, many American police departments have adopted written policies & procedures detailing what constitutes acceptable use of facial recognition technology. A Model Facial Recognition Use Policy, based upon actual department manuals, can be found in the link at the end of this article.
They generally include specific guidelines covering the limitations upon acceptable use; they also explain the qualification and training for users, who are often called Facial Examiners in many departments. The standards for both Field Identification and Investigative Use are included.
You may access the complete text of the model policy here.