Suppose Alice and Bob are talking about a big drug deal over the phone, and Carol (working for the NSA) listens in. Carol lets her friend Dan know, and Dan's a police officer so he goes on a stakeout and catch Alice and Bob in the act, with $1M of cocaine in the trunk of Alice's car, and $1M of cash in the trunk of Bob's car. Open and shut case, right?
US case law states that the cocaine is "fruit of the poisonous tree", because the cocaine would never have been discovered by the police if it weren't for the illegal wiretap. Therefore it is inadmissible as evidence. The prosecution's case is sunk, and Alice and Bob go free. (Note that Dan never committed any crimes, might not be aware of the wiretap, and got good, hard, physical evidence that Alice and Bob were breaking the law.)
So if the government tries to use an illegal wiretap in an actual criminal case, it will probably do the prosecution more harm than good. Best chance for a conviction is to pretend the wiretaps never happened.
Edit: I think a good example here is "Nardone et al. v. United States." In this case, Nardone was convicted of smuggling alcohol etc. during a first trial based primarily on evidence acquired through illegal wiretaps. This conviction was overturned because the wiretaps were not admissible as evidence. On the second trial, Nardone was convicted again on other evidence. This conviction was also overturned, because the prosecutors wouldn't have had this evidence if it weren't for the wiretaps.
> Best chance for a conviction is to pretend the wiretaps never happened.
And this is why PRISM coming to light is a good thing as it gives the defense another reason to question intent, in the scenario above it would be Bob and Alice asking why Dan was staking out their house and searching their cars.
Also, let's be clear, and stop saying "the government". Let's say "the NSA" is doing the wiretap. Then we can talk about "state prosecutors" or "federal prosecutors", and talk about how those prosecutors ended up with evidence obtained by tainted means.
> Just as the suppression of evidence does not require the return of such items as contraband, the introduction of "mere evidence" does not entitle the State to its retention if it is being wrongfully withheld. Pp. 307-308.
So just because the cocaine can't be used as evidence, doesn't mean that the police have to give it back -- it's still contraband. Maybe they would destroy it if they have no other use for it. But Alice would get her car back, if it were seized with the cocaine.
As for future prosecution, nobody is exempt, but the prosecution would probably have to come up with new charges (due the fifth amendment double jeopardy clause). Waiting a few weeks would not change legal circumstances and a judge would see right through such trickery, but if I were Alice or Bob I would keep my nose clean for a while.
No. They don't have to return illegal contraband found during an improper search, but it cannot be used as evidence in a trial against them.
Suppose that Alice has two kilos of Cocaine in her refrigerator, and then she breaks into Best Buy and steals a 72" TV. She gets caught on camera, but they're not sure it's her, so the police get a warrant to search her house. One officer goes into the attic and finds a 72" TV... bingo, she's gonna get convicted.
But another officer was in the kitchen, and found the Cocaine. No conviction. It's a legal search since they have a warrant, but the police can't use the Cocaine in the fridge as evidence, because they have a warrant to find a 72" TV. The fridge is too small for a 72" TV, so the police can't look in the fridge, and they can't use anything they find in the fridge as evidence.
Alice gets busted for stealing a 72" TV, but the conviction for Cocaine gets thrown out.
So, back to the wiretaps. Just because a wiretap is legal doesn't mean that all the evidence you get from a wiretap will be admissible as evidence.
Second, calling the wiretaps legal does not make them so. The courts might declare that they're illegal without a warrant.
Third, it's the executive branch that calls the wiretaps legal. We should be at least this specific. The executive branch can claim PRISM is legal, but only the judicial branch has the power to actually decide on the legality.
http://news.cnet.com/8301-27080_3-20007827-245.html?part=rss...
Also, even if the warrant was overbroad, the evidence wouldn't get thrown out as fruit of the tainted tree, because a bad decision by a judge (e.g. grant a bad warrant) won't cause the evidence to become tainted in that way. You can exclude evidence because the police broke the law, but the judge isn't breaking the law just by interpreting it poorly. Or put another way, we don't want the police to have second-guess judges' decisions.