False evidence, fabricated evidence, forged evidence, fake evidence or tainted evidence is information created or obtained illegally in order 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, e.g. to prove that the accused was not at the scene of the crime when it was being committed.

In June 1970 a Pukekawa, Lower Waikato, couple were killed and their bodies dumped in the Waikato River. Arthur Allan Thomas, a local farmer, was twice convicted of their murders but following massive publicity was later given a royal pardon.

Two bullet cases presented by senior detectives Bruce Hutton and Lenrick Johnston were crucial evidence for the conviction. In 1980, after Thomas's pardon a Royal commission into the convictions concluded "Mr Hutton and Mr Johnston planted the shellcase, exhibit 350 in the Crewe garden, and that they did so to manufacture evidence that Mr Thomas's rifle had been used for the killings."

In 1975, after the shooting death of Bernard Whitehurst by a Montgomery, Alabama police officer who incorrectly identified Whitehurst as the suspect in the robbery of a neighborhood grocery store, there was a police cover-up that included police officers planting a gun on him from the police evidence room. The coroner relied on police reports that Whitehurst was killed by a bullet fired through the chest. After an investigation by the local newspaper and local attorney Donald Watkins raised questions about the facts of the case, six months later, the District Attorney James Evans ordered the body to be exhumed and an autopsy to be performed. The results of the autopsy showed that Whitehurst had been shot in the back. The attempted cover-up led to the resignation of eight police officers, the city’s mayor, James Robinson and the Director of Public Safety, Ed Wright. No police officer was convicted of a crime. Forty years later, the Montgomery City Council passed a resolution that formally expressed regret for the shooting and cover-up.

In 1992, 11-year-old Holly Staker was raped and murdered while babysitting in Waukegan, Illinois. A local man named Juan Rivera was convicted of the murder solely on the basis of a confession, one that he claimed was coerced. No physical evidence linked him to the crime scene and many details of his confession contradicted known evidence from the crime scene. DNA testing done in 2004 on semen taken from the crime scene ruled out Rivera as the source, however, the prosecution argued that the semen sample came from previous consensual sex with another man. Rivera was convicted again. His conviction was overturned by the appellate court who took the unusual step of barring prosecutors from retrying Rivera and he was released.

After his release, Rivera's attorneys asked the courts to order genetic testing on a piece of evidence the prosecution had tried to use at his trial in 1993. Rivera's shoes had blood on them, which the prosecution argued belonged to Holly. The prosecution withdrew them prior to his first trial when it was discovered that the shoes were not available for sale anywhere in the United States until after the murder. In 2015, Juan's attorney sought further forensic testing on the shoes. DNA analysis indicated that the blood indeed belonged to Holly, but also contained another genetic sample; one that matched the semen sample. Rivera's defense team insists that this is proof not only that the blood was planted, but that the real killer's DNA was inadvertently planted as well. The DNA has yet to be matched to an individual, but has been linked to DNA from another home invasion and murder. The man convicted of that crime also claims to be wrongfully convicted.