[vkou]

Why would it be?

The purpose of laws like the 4A is to prevent the police from harassing innocent people by going on fishing expeditions. The purpose of the poisoned tree doctrine is to prevent the police from committing crimes as part of their work.

But if a plains-clothes police officer sees you load a kilo of cocaine into your car every Tuesday, on the same street corner, there's nothing illegal or immoral about him telling a uniformed cop to show up next Tuesday, to observe you doing just that. I see no reason why the uniformed cop should be compelled to reveal his source.

Now, if the plains-clothes officer was doing warrant-less break and entry in order to observe you doing the crime, that would be an ethical problem.

This does create a bit of a connundrum - where you often can't tell if parallel construction was used to cover for legal, or for illegal behaviour. But I see no reason for why the first case I presented should be forbidden. If pressed on the stand as to why the officer chose that street corner to be on Tuesday, they can avoid prejury by declining to answer, or just say that they were tipped off. I find it doubtful that a judge would compel the officer to answer, or to elaborate - he's not the one that's on trial, after all.

[seniorivn]

in your analogy, plains-clothes officer breaks into the private property without leaving a trace, by using unknown vulnerabilities in security of the place, leaves with evidence without being noticed gives that evidence to a supposedly uninformed cop, and development of that case leads to prosecution of the property owner. And you are saying there is nothing sketchy about that?

[vkou]

> And you are saying there is nothing sketchy about that?

It all hinges on whether or not they had a warrant to surveill the ISIS site.

If the police have a warrant to plant a hidden camera at a crackhouse, I don't see why they would have to reveal its existence, when they later stop and search a car full of drugs at a perfectly legal search at a border checkpoint. If they didn't have a warrant... That's an ethical problem, and it runs afoul of the fruit of the poisoned tree.

Likewise, if there's an informant or a mole at the crackhouse, do you think the police are obliged to notify the world of his identity, every time they arrest someone he tips them off to?

[oldgradstudent]

> I see no reason why the uniformed cop should be compelled to reveal his source.

If the defense asks at trial, what legitimate reason is there not to answer?

[vkou]

The legitimate reason is that it's not pertinent to the case. The accused is on trial, versus evidence publicly presented against him. If the prosecution feels that the evidence they would like to reveal in the trial is sufficient for a conviction, they have no reason to throw in 'Oh, and we have an informant who's been snitching on you and your fellow conspirators.'

It's not exculpatory evidence, there is no obligation for the prosecution to turn it over. There's no reason for the judge to allow a line of questioning into it unless the defendant can make an argument as to why its relevant.