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. By the United States Drug Enforcement Administration In August 2013, a report by Reuters revealed that the Special Operations Division (SOD) of the U.S. Drug Enforcement Administration advises DEA agents to practice parallel construction when creating criminal cases against Americans that are based on NSA warrantless surveillance. The use of illegally obtained evidence is generally inadmissible under the fruit of the poisonous tree doctrine. Two senior DEA officials explained that the reason parallel construction is used is to protect sources (such as undercover agents or informants) or methods in an investigation. One DEA official had told Reuters: "Parallel construction is a law enforcement technique we use every day. It's decades old, a bedrock concept." An example from one official about how parallel construction tips work is being told by Special Operations Division that: "Be at a certain truck stop at a certain time and look for a certain vehicle." DEA would alert state troopers and they may wait for that certain vehicle and decide to use drug searching dogs to see if there is any illegal drug-related activity. Parallel construction allows the prosecution building the drug case to hide the source of where the information came from to protect confidential informants or undercover agents who may be involved with the illegal drug operation from endangering their lives. A number of former federal agents had used parallel construction during their careers, according to Reuters interviews. Most of the former agents had defended the practice of parallel construction because, according to them, no falsified evidence or illegally obtained material were presented in courts.. A judge can rule evidentiary material inadmissible if it is suspected that the evidence was obtained illegally. Parallel construction in this case in the US usually is the result of tips from the DEA, as well as