The 4th Amendment to the U.S. constitution places limits on the power of the police to make arrests, search people and their property, and seize objects. These limits are the foundation of search and seizure law. That means that a police officer cannot arrest you, search your person, search your property, or seize your property unless he has probable cause to do so. Probable cause can be defined as sufficient facts that would lead a reasonable person to believe that a crime has been committed.

The Fourth Amendment to the U.S. Constitution reads as follows:

“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.”

The search and seizure provisions of the Fourth Amendment are all about privacy. The Fourth Amendment applies to a search if, and only if, a person has a valid “expectation of privacy” in the place or thing being searched. In order for there to be a legitimate expectation of privacy, any reasonable person would have to also expect privacy given the same circumstances. If you do not have a reasonable expectation of privacy in the place searched or in the items seized, there is no Fourth Amendment violation.

On the other end,  the Fourth Amendment does permit searches and seizures that are considered reasonable. This means that the police may conduct a search, regardless of your privacy concerns, if:

• they have probable cause to believe they can find evidence that you committed a crime, and a judge issues a search warrant, or;
• the particular circumstances of your case justifies the search without a warrant.

A search warrant permits California police to search you, your home, your car and any other specified area that they suspect has evidence of illegal activity. The search warrant allows them to seize that evidence if they find it. It is up to the defendant to prove that the search was illegal. They can do this by:

• proving that the officer who requested the search warrant purposely misled the judge about the facts justifying the warrant;
• proving that the warrant was not specific enough with regards to the place to be searched or the things to be seized;
• and/or proving that the judge who issued the warrant made a bias decision and did not contain a neutral role.

However, police are permitted to conduct searches without a warrant, in the following situations:

1. “Exigent circumstances.” These are circumstances that would cause a reasonable person to believe that entry (or other relevant action) is necessary to prevent physical harm to the officers or other people, the destruction of relevant evidence, the escape of the suspect, orsome other consequence.
2. When a person freely and voluntarily consents to a search.
3. Inspections: security searches, border searches, health inspections, and California DUI sobriety checkpoints/ driver’s license checkpoints (part of the “automobile exception” to warrant-less searches).
4. The “automobile exception”. For the most part, the automobile exception provides that warrant-less searches of automobiles are permitted when the police reasonably believe a vehicle holds evidence of a crime. It is based on the fact that drivers have a reduced expectation of privacy in a car and that cars are mobile, allowing the chance for evidence to be easily moved and destroyed.
5. The “plain view” doctrine. Once the police have the authority to search an otherwise “protected” area, the police are permitted to seize any items that are in “plain view” where there is probable cause to believe that the item is evidence.
6. There is no reasonable expectation of privacy. If one does not have a reasonable expectation of privacy in the place searched or items seized, there is no Fourth Amendment protection.
7. Immediately following an arrest. At that time an officer is allowed to search the arrested individual and the area “within the individual’s immediate control” in order to seize any weapons or evidence.

So what happens if a police officer conducted a search illegally and violated your fourth amendment rights? If a court finds that an unreasonable search occurred, any evidence seized as a result of the search cannot be used as direct evidence against the defendant in a criminal prosecution, state or federal. This is known as the “exclusionary rule.”

The “fruit of the poisonous tree” doctrine stems from the “exclusionary rule.”  It states that any evidence obtained during an illegal search, cannot be used to obtain other evidence. The “tree” would be the evidence that was illegal seized first, and the “fruit” would be any evidence seized because of the “tree.” For example, if the police unlawfully searched a home and found a key to a gym locker (tree), and then later found drugs in the locker (fruit), both would be inadmissable at trial.

Although the evidence is inadmissable, some defendants believe that if they can show that a search was illegal, the case must also be dismissed. Unfortunately, this is not true. If a prosecutor has enough other evidence to prove the defendant guilty, the case can continue. If the case does continue, the judge can later use the evidence when deciding sentencing. It can also be used against you in civil and deportation.