About how signals intelligence agencies, like NSA and GCHQ, are intercepting communications, we learned a lot from the Snowden revelations, the German parliamentary inquiry, but also from new legislation in France, the Netherlands and the United Kingdom.
Much less is known about the practice of tapping by law enforcement, like for example the FBI and police forces. Now, a case from the Netherlands provides some interesting insights in how Dutch police intercepts internet communications - in a way that comes remarkably close to the bulk collection by intelligence agencies.
http://electrospaces.blogspot.com/2017/06/dutch-russian-cyber-crime-case-reveals.html