US cop-TV shows often treat it as a given, but US courts allow in bad evidence more often than not. US supreme court decisions are generally against the exclusionary rule, and it's likely to mostly disappear in the US in the near future, except for very rich defendants. Here's the most recent one:

https://en.wikipedia.org/wiki/Hudson_v._Michigan

where everyone involved says the evidence was seized improperly, unconstitutionally, but the evidence is very much in and the defendants are in prison today.