The Fourth Circuit has rejected a request to apply the full scope of the exclusionary rule to evidence obtained in violation of the Fourth Amendment and used by the government in Immigration Court proceedings.  The court affirmed that the exclusionary rule is only applicable in cases of egregious violations of the Fourth Amendment.  This standard applies when state or local law enforcement violate the Fourth Amendment, as well as when federal officials commit the violation.  "A stop or seizure based solely on an abuse of an officer’s legal authority and without reasonable suspicion of criminal activity will usually be egregious."  

The full text of Sanchez v. Sessions can be found here: