This is the basic idea of the good faith exception to the exclusionary rule. The exclusionary rule was supposed to deter police misconduct (e.g., searching a house without a warrant, thereby violating the Fourth Amendment) by preventing them from using evidence they never should have had. But the deterrence rationale doesn't hold up that well when the police reasonably (and that's key) believed that they were acting lawfully.

'Your constitutional rights were violated but tough luck, nothing can be done about it because the court is extending special 'good faith' courtesy to the police that you don't get (some animals are more equal than others in court decisions/considerations when minor laws (the fourth amendment) are broken)'.

And people wonder why American's are apathetic to it all. A judge can just wave away constitutional violations all day/every day because 'good faith'.