The interviewer wrote: "Payne says that despite the seeming 'benign' nature of the requirement to respond to a request for ID or display it, there's no path to make it mandatory. It's not a constitutional issue, he notes, and the federal government has no basis on which it can demand thousands of agencies meet any specific guidelines."
Read the article:
"Think you have the right to have police identify themselves? Look closer." by Glenn Fleishman. Boing Boing, 25 Feb 2015. (This article includes the Anchorage Police Department policy.)