Falsification of evidence

False evidence, fabricated evidence, forged evidence or tainted evidence is information created or obtained illegally, to sway the verdict in a court case. Falsified evidence could be created by either side in a case (including the police/prosecution in a criminal case), or by someone sympathetic to either side. Misleading by suppressing evidence can also be considered a form of false evidence (by omission), however, in some cases, suppressed evidence is excluded because it cannot be proved the accused was aware of the items found or of their location. The analysis of evidence (forensic evidence) may also be forged if the person doing the forensic work finds it easier to fabricate evidence and test results than to perform the actual work involved. Parallel construction is a form of false evidence in which the evidence is truthful but its origins are untruthfully described, at times in order to avoid evidence being excluded as inadmissible due to unlawful means of procurement such as an unlawful search.

Apart from the desire for one side or another to succeed or fail in its case, the exact rationale for falsifying evidence can vary. Falsifying evidence to procure the conviction of those honestly believed guilty is considered a form of police corruption even though it is intended to (and may) result in the conviction of the guilty; however it may also reflect the incorrect prejudices of the falsifier, and it also tends to encourage corrupt police behavior generally. In the United Kingdom this is sometimes called 'Noble Cause Corruption'. A "throw down", i.e. the planting of a weapon at a crime scene might be used by the police to justify shooting the victim in self-defense, and avoid possible prosecution for manslaughter. However, the accused might have falsified some evidence, especially if not arrested immediately, or by having other access to a crime scene and related areas.

In some criminal cases, a person will be identified as a "person of interest" for a few days before arrest, allowing time to reveal suspicious actions (such as in recorded phone calls), or to attempt to falsify evidence before their arrest. A type of falsified evidence, used to acquit, would be faked sales receipts which indicated activities (with the accused) had occurred elsewhere during the time of the crime.

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