What legal principle is applicable when obtaining evidence in violation of a person's constitutional rights?

The Fruit of the Poisonous Tree Doctrine is a legal principle that asserts any evidence obtained through unconstitutional means, such as an illegal search or a coerced confession, is tainted by that illegality and thus inadmissible in court. This doctrine extends from the Exclusionary Rule, which generally bars the use of evidence that violates a person's Fourth Amendment rights. Essentially, if the initial evidence (the "tree") is obtained through unconstitutional actions (the "poison"), then any subsequent evidence derived from it (the "fruit") is also inadmissible.

This principle is pivotal in protecting constitutional rights by discouraging law enforcement from using unlawful methods to gather evidence. It emphasizes the importance of adhering to legal standards in the pursuit of justice and reinforces the expectation that evidence must be obtained fairly in order to be presented in legal proceedings.