Wales Police Force strip search scandal). The law was reviewed in 2006 by the New South Wales Ombudsman, who handed down a critical report regarding the use of dogs for drug detection. The report stated that prohibited drugs were found in only 26% of searches following an indication by a drug sniffer dog. Of these, 84% were for small amounts of cannabis deemed for personal use. The report also found that the legislation was ineffective at detecting persons in supply of prohibited drugs, with only 0.19% of indications ultimately leading to a successful prosecution for supply. United States In 2011, civil rights activists claimed that detection dogs responses are influenced by the biases and behaviors of their handlers, which can hinder accuracy. Another factor that affects accuracy is residual odors. Residual odors can linger even after illegal materials have been removed from a particular area, and can lead to false alarms. Additionally, very few states have mandatory training, testing, or certification standards for detection dogs. This leaves people to question whether they are truly equipped to carry out searches. Sniffer dogs can be trained to detect crop pests and diseases. A study by the US Department of Agriculture found that sniffer dogs identified trees infected with citrus greening disease with 99% accuracy; they could detect infection as early as two weeks after onset. Civil rights Detection dogs give police the potential to conduct searches without cause, in a manner that is unregulated. They are often accused of being motivated more by the state's desire to be seen doing something than by any serious desire to respond to the dangers of drugs use. In June 2012, three Nevada Highway Patrol officers filed suit against Nevada's Director of Public Safety, alleging that he violated the police dog program by intentionally training canines to be "trick ponies" to falsely alert based on cues from their handlers (Clever Hans effect) so as to enable officers to conduct illegal searches of vehicles. The lawsuit claims that in doing so, he and other top Highway Patrol officers had violated the federal Racketeer Influenced and Corrupt Organizations Act (RICO Act). In Norway, students were subjected to a drug search in their classroom by a detection dog. The students didn't have to be present in the room while the dogs searched; however, they were forced to answer questions by the police instead. An article in Tidsskrift for strafferett,