--The Exclusionary Rule
The Exclusionary Rule pertains to evidence that is gathered or attained from an illegitimate search and seizure, a method that is in violation of the Fourth Amendment. The Fourth Amendment to the Constitution is meant to protect the individual's privacy in its prohibition of government intrusion.
In addition, the Exclusionary Rule applies to the Fifth Amendment because it protects people from self-incrimination by prohibiting the improper attainment of statements that are self-incriminatory.
It also applies to the prohibition of evidence attained improperly. That is, if evidence that is gathered in violation of the Fourth Amendment leads police to other evidence that would not be otherwise attained, then the Exclusionary Rule applies to both the initial evidence and the related evidence, as well. [https://www.law.cornell.edu/wex/exclusionary_rule]
--Why the Exclusionary Rule is disturbing
The prohibition of evidence gathered through great effort and time often is very disturbing to police because the officers may have assumed that this evidence was gleaned legally, having been unaware that the Exclusionary Rule was previously broken. Also, when the police see guilty people go free simply because of procedural mistakes (e.g., forgetting to read a suspect his/her Miranda Rights) they probably feel very frustrated that a known criminal has escaped the law.
--How police can work around the Exclusionary Rule
Although police have been known to skirt corners in their eagerness to have a criminal convicted, many work harder to attain substantive evidence legally.
Also, under what is called the good-faith exception, evidence obtained by officers who have relied upon a search warrant that turns out to be invalid is still admissible. [Arizona v. Evans, 514 U.S. 1 (1995)]
--Does the Exclusionary Rule protect individuals more or help police?
The Exclusionary Rule seems to be more protective of people as it prohibits the violation of their privacy and it ensures that police are better trained in executing the law.