American law, abandonment confers no right in a suspect to challenge the government's seizure of evidence without a search warrant.  Under our constitutional law, the government generally needs a search warrant, but abandonment is one of the exceptions for which no warrant is needed.  And this is a very effective law enforcement tool that makes it easy for them to do their job.  I have a case now where the client, a boxer, was suspected of having committed bank robbery in 2009.  An FBI agent did some background search on him, found out from Facebook he was a boxer in Toledo, Ohio, went to one of his boxing matches and lo and behold, he discarded a q-tip with blood on it from a bloody nose.  Guess what . . . the agent took the bloody q-tip to the crime lab, compared it against DNA found on a face mask the suspect left at the scene and got a MATCH!  Bam!  He was charged and convicted.  Facing a minimum of 20 years next month at sentencing.  He could not even challenge the lawfulness of the agent's actions because he discarged the bloody q-tip in a trash can.  Abandonment.  Agent does not need a search warrant.  Easy for them.