Parallel construction

Parallel construction is a law enforcement process of building a parallel, or separate, evidentiary basis for a criminal investigation in order to conceal how an investigation actually began.

In the US, a particular form is evidence laundering, where one police officer obtains evidence via means that are in violation of the Fourth Amendment's protection against unreasonable searches and seizures, and then passes it on to another officer, who builds on it and gets it accepted by the court under the good-faith exception as applied to the second officer. This practice gained support after the Supreme Court's 2009 Herring v. United States decision.