So, it is (or was) a common misconception that police can't lie if you ask them directly if they're police. It's a misconception among prostitutes that, if you ask the john "are you a cop", the cop can't arrest you if they lie.
Now, this is obviously false. Most things an ordinary citizen can do, a cop can do in the collection of evidence. Cops regularly do things like pretend to be electricians or plumbers to gain access to suspect's homes, and that's usually legal.
If it constitutes a search, and it probably would, they need a warrant or exigent circumstances, or some legal justification for doing it beyond merely that they felt like it. Also, most warrants require knocking and announcing to be executed. For surreptitious surveillance, they need more of a justification.
There are ways of going about this. For instance, getting permission from at least one person at the premises.
But how far does it go?
The other day, a city building inspector asked me to unlock the sally port next to my door so she could look at the neighbors backyard. It's not my place to be letting random people into my neighbor's backyard, so I checked her ID. She also gave me a business card. Impersonating a city official is probably illegal and so because of the principle of the
fruit of the poisonous tree, any evidence acquired while impersonating a city official would be thrown out.
And this got me thinking: how far does this principle go? And how far should this principle go? What do you guys think?
It's difficult to say exactly how far it goes, because the case law is all over the place in at least the contested areas.
There are tons of exceptions to the exclusionary rule, too, such as the doctrine of inevitable discovery, independent source, etc. Fruit of the poisonous tree generally only applies when the misconduct is the source of the evidence and it wouldn't have been discovered otherwise.
For instance, suppose police illegally search a car during a stop and it would have otherwise been impounded and searched, regardless of circumstances. If the evidence would have inevitably been discovered anyway, the exclusionary rule doesn't apply. Similarly, if the police obtained evidence from two places, one of them illegally, and the source of the legitimately obtained evidence is unconnected with misconduct, the evidence gets in.
Like the hearsay rule, the exclusionary rule has as many holes in it as Swiss cheese.
Remember, the exclusionary rule should be limited in scope because it has absolutely nothing to do with the guilt or innocence of the suspect. In fact, it only applies to evidence admitted in a criminal case, that is, it only directly affects those who are very likely guilty. It doesn't depend on the evidentiary value of the material. In fact, most evidence excluded under the rule is strong evidence of guilt, or there wouldn't be any objection to admitting it.
The rule basically protects the guilty in its direct action. As (future) Supreme Court Justice Cardozo said of the rule: "The criminal is to go free because the constable has blundered." That is, the rule punishes misconduct by the police, but not by directly punishing the police. It instead punishes society, by letting go a probably guilty criminal.
The reason for this is indirect benefit. It only benefits society at large, and innocent people, by dissuading law enforcement from rampantly engaging in illegal searches, because they know they won't benefit from it. In fact, their cases will be thrown out to the extent they rely on illegally obtained evidence. Therefore, there are less illegal searches of innocent people because there must be a particularized suspicion to justify a search, that is, the police must already know enough that they are less likely to search innocent people incorrectly.
So the rule should only go as far as necessary to preserve its deterrent effect. There is no general "right to get away with a crime if the police screw up."
