The PD that I was associated with has had its Standard Operating Procedures on-line off and on over the years as policy makers have come and gone. At the moment they are not on-line. When I wanted one to use in a discussion here some years ago, it was made available at my request.
I am sure that they are available through a Freedom of Information Request, having been developed at taxpayer expense.
It is not likely that legal conclusions will be standardized, the devil being in the details.