One way this can happen is due to the exclusionary rule. The US Supreme Court has said that States have a Constitutional duty to make sure unconstitutionally seized evidence is not used against a person.
If it can be shown that evidence was seized was in an unconstitutional way, the defense can file a motion to quash arrest and suppress evidence. This is not a motion to dismiss; it is a motion that prevents the State from using the illegal evidence. It is starving their case. This motion is all about keeping illegal evidence out.
The 4th, 5th, 6th Amendments have an exclusionary Rule. An attorney can try to exclude contraband, identifications, or confessions.
Insofar as drug cases, trials can become irrelevant because the suppression hearings can be everything.
According to the 4th Amendment,
· “The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."
Basically, the framers were not thinking of street crime. The Fourth Amendment arose because the British would go onto middle class property and see if everything checked out on their taxes. There are 2 clauses to the Fourth Amendment. One is a restriction to unreasonable search and seizure by the government. The second is directions to law enforcement to get a warrant you must conform to this. The guiding principle in this area is reasonableness of the search and seizure.
The Exclusionary Rule is not mentioned in the Constitution, it is a creature of subsequent case law. When it was drafted there were no street cops as we have today. So what does the 4thAmendment say on how cops should act? Nothing; the founders had no clue about this. The answer that is settled on is that every generation has to find out for itself.