The "exclusionary rule" allows judges in criminal cases to disregard ("exclude") evidence that has been illegally obtained by police.
Illegal police searches in Colorado
Police are required to adhere to the Fourth Amendment's prohibition against unreasonable searches and seizures when conducting searches. In general, police are required to secure a Colorado search warrant prior to executing a search.
In order for these search warrants to be valid, they must indicate with specificity the locations to be searched and the items to be seized, and they must be supported with probable cause that a crime has taken place. Unsupported, vague, or overbroad search warrants can be voided as unconstitutional.
Even if a search warrant is valid, police may not go beyond the bounds of the warrant (with some exceptions). Police who do not have a legal reason to search and seize property outside the bounds of the warrant are violating the Fourth Amendment.
Meanwhile, police searches done without a warrant are usually unlawful unless the circumstances fall under a legal exception, such as:
- the owner of the property consented to being searched;
- there were emergency ("exigent") circumstances that justified not getting a warrant first;
- the police were in "hot pursuit" of a fleeing suspect;
- the evidence was in "plain view" of the police;
- the search was incident to a lawful arrest;
- the search area is a vehicle as long as the police have probable cause to believe the car contains evidence of a crime ("the automobile exception"); and/or
- the search is a "stop and frisk" of a person the police reasonably suspect has committed a crime
In short, police must respect people's reasonable expectation of privacy and may not execute searches without meeting Fourth Amendment prerequisites.
Motions to suppress in Colorado
When a person is charged with a crime, the defense attorney will investigate whether the evidence against the defendant was lawfully obtained through a legal search. If any evidence may have been procured in contravention of the Fourth Amendment, the defense attorney would file a motion to suppress evidence with the court.
The theory behind motions to suppress is that any evidence that is found through an unlawful search is tainted. Therefore, it is only fair for this unlawfully-obtained evidence to be inadmissible ("suppressed") at trial.
Note that the exclusionary rule applies not only to the original evidence that was illegally-obtained but also to any new evidence that that illegally-obtained evidence lead police to ("the fruit of the poisonous tree").
There are some exceptions to the exclusionary rule where evidence that was illegally obtained could still be admitted at trial:
- The police relied on a search warrant they genuinely believed was valid ("good faith exception");
- The evidence at issue was only remotely related to an illegal source ("attenuation doctrine");
- The police obtained the evidence at issue from an independent source ("independent source doctrine"); and/or
- The police would have discovered the evidence at some point anyway ("inevitable discovery rule")
Colorado courts typically hold hearings to decide whether or not to admit evidence that may have been illegally obtained. The prosecution presents evidence arguing why the evidence should be admitted, and the defense attorney argues why the evidence should be suppressed. If the judge decides to suppress the evidence, the prosecution may be left with insufficient evidence to win a guilty verdict at trial.