Here is a recent court judgement coming from the Supreme Court in New York State relating to the use of an informant and establishing probable cause.
This document contains quite a few references to other cases on which the judgement was based.
Reading such cases enables officers to ensure that the guilty are not acquitted on a technicality.
In this case the appellant’s lawyers seem to have adopted a shotgun approach questioning everything. Fortunately the officers involved had done their job well and all the ducks were in a row.
