[EthanHeilman]

(i). Intelligence Agency informs police that someone might be doing something bad. Police hide the source of the tip using parallel construction. Thus, an intelligence agency has made an allegation of criminal wrong doing.

(ii). The initial allegation may turn out to have been a mistake, but it is never examined in a court of law. Whatever evidence they "construct", such as anonymous tips or circumstantial evidence may be very hard to refute in court. The investigation begins to take on a life of its own.

[tptacek]

The police make arrests. Prosecutors make charges. Charges need to be accompanied by evidence. Evidence often comes from arrests; arrests circumvent the search warrant requirement ("search incident to arrest"), meaning that the cause for an arrest is subject to challenge. Intelligence agencies can't generate cause for arrest and they can't generate charges.

Anonymous tips don't remain anonymous in court. The way you get evidence from a CI is to use their info to request a warrant. The warrant identifies the CI. Surveillance data can't be a substitute for a CI in that scenario, because a warrant can't issue from surveillance data the way it can from a CI. And, of course, for someone to be charged based on an anonymous tip, the search effected by the warrant has to turn up evidence of a crime.

[wan23]

It's like the episode of The Wire where Herc and Carver plant a remote microphone inside a tennis ball to listen in on some drug dealers and attribute their evidence to a non-existent confidential informant named 'Fuzzy Dunlop'. They need to invent a CI because they hadn't previously convinced a court of the need to surveil those persons and so they had nothing they could use in a trial. I'm not a lawyer so I can't say if the legal issues depicted were depicted accurately, but I recommend the show to anyone interested in the topic of surveillance for the purposes of law enforcement (as opposed to intelligence gathering) and how things can potentially go wrong despite their good intentions.

[DelightfulScone]

"Anonymous tips don't remain anonymous in court."

Evidence can and is withheld from defense using mechanisms like States Secrets.

[tptacek]

State secrets is a mechanism to exclude evidence, not introduce it.

[DelightfulScone]

That's why I said withheld, yes.

[tptacek]

So how do state secrets privileges introduce anonymous evidence? Maybe at this point it would be helpful for us to have a specific case to refer to. Could you point us to one?

[DelightfulScone]

"So how do state secrets privileges introduce anonymous evidence?"

By allowing anonymous evidence to be introduced, obviously.

"Regulatory "Executive Privilege" to Withhold Evidence," Indiana Law[0]

[0] http://www.repository.law.indiana.edu/cgi/viewcontent.cgi?ar...