Inevitable Discovery: Rule, Doctrine & Exception

Instructor: Janell Blanco
This lesson will discuss inevitable discovery and the important rules that apply to law enforcement agents. We will also discuss inevitable discovery doctrine and exceptions.

Inevitable Discovery

Did you know that the Fourth Amendment protects you from illegal search and seizures? What happens though when the law enforcement agents do not have consent to search or do not have a warrant to search and they find illegal items?

This is where inevitable discovery comes into play. Inevitable discovery is the law that states evidence that was found using illegal means could still be admissible in court if the evidence would have been found eventually anyway using legal means. Inevitable discovery basically means that the officers would have found the evidence legally eventually.

For example, say Johnny told the police he did not start any fires in the area. The officers popped the trunk of Johnny's car and found a gas can. The fires were started with gas and a witness placed Johnny at the scene of the fire before the fire started. The officers opened the trunk without consent but they would have been able to get a warrant to search the vehicle. The gas can was found illegally because they did not have consent to search, but they would have inevitably obtained a signed warrant to search the vehicle. This would be inevitable discovery.

They may have obtained the evidence illegally, but the courts can show that the officers would have eventually found the evidence legally, thereby making it admissible in court cases. However, there are exclusions to the inevitable discovery rule.

Exclusionary Rule

The exclusionary rule states that when evidence has been seized in an illegal manner, it may be inadmissible in court. The exclusionary rule is in place to protect the public from police misconduct and to ensure that search and seizures are completed lawfully.

However, if the primary or derivative evidence was going to be found anyway, then it may be permissible in court. Additionally, if the evidence would not have been found with inevitable discovery, then it is not allowed in court. Let's take a look at which evidence is permitted in court with inevitable discovery.


Primary evidence is the evidence that is seized because it is directly related to the crime. An example of primary evidence would be a bag of marijuana. Derivative evidence is the secondary evidence, such as drug paraphernalia or drug residue within the car's ashtray.

The Supreme Court allows only for derivative evidence to be allowed as evidence under the inevitable discovery rule. While state courts also allow derivative evidence to be used, some state courts may allow primary evidence to be used in a case as well.

Another exception is the good faith exception. What if the officer was working in good faith when he found the evidence?

If an officer had completed a search and seizure with a warrant that later was found to be invalid, the evidence would be allowed. The officer found the evidence on the good faith that the warrant was correct and valid. One last item we will discuss is what happens if the evidence was discovered with the assistance of illegal means, but the officers would have found it later in the investigation.

Fruit of the Poisonous Tree Doctrine

There is an extension of the exclusionary rule that pertains to inevitable discovery, known as the Fruit of the Poisonous Tree Doctrine. This doctrine established the law that information obtained with the assistance of illegal means is not permissible in court unless one of the following three items can be proven.

  • The information obtained would be inevitably discovered
  • A person independent of the investigation provided the information
  • There is a long period of time between the crime and the discovery of evidence

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