In legal context, what does 'tainted evidence' refer to?

Tainted evidence refers to any evidence that has been collected or obtained through illegal means, which fundamentally undermines its admissibility in a court of law. This includes circumstances where law enforcement may have violated constitutional rights, such as conducting illegal searches without a warrant or obtaining statements under duress. The legal principle behind this is the exclusionary rule, which aims to deter police misconduct and ensure that only evidence gathered in accordance with the law is presented in court.

The other options describe various concerns related to evidence, such as alteration, irrelevance, or lack of authorization, but they do not encapsulate the specific legal concept of 'tainted evidence' as accurately as the correct answer does. Evidence obtained illegally remains a crucial aspect in the context of ensuring fair trials and maintaining justice within the legal system.