a larger percentage of shipping to be checked for smuggled items, weapons, drugs, or people. There are also gamma-ray-based systems coming to market. In May 2011, the Electronic Privacy Information Center filed suit against the United States Department of Homeland Security (DHS) under the Freedom of Information Act, claiming that DHS had withheld nearly 1000 pages of documents related to the Z backscatter vans and other mobile backscatter devices. Concerns Legality Since in addition to weapons, these machines are designed to be capable of detecting drugs, currency and contraband, which have no direct effect on airport security and passenger safety, some have argued that the use of these full body scanners is a violation of the 4th Amendment to the United States Constitution and can be construed as an illegal search and seizure. Privacy Backscatter x-ray technology has been proposed as an alternative to personal searches at airport and other security checkpoints easily penetrating clothing to reveal concealed weapons. It raises privacy concerns about what is seen by the person viewing the scan. Some worry that viewing the image violates confidential medical information, such as the fact a passenger uses a colostomy bag, has a missing limb or wears a prosthesis, or is transgender. The ACLU and the Electronic Privacy Information Center are opposed to this use of the technology. The ACLU refers to backscatter x-rays as a "virtual strip search". According to the Transportation Security Administration (TSA), in one trial 79 percent of the public opted to try backscatter over the traditional pat-down in secondary screening. It is "possible for backscatter X-raying to produce photo-quality images of what's going on beneath our clothes", thus, many software implementations of the scan have been designed to distort private areas. According to the TSA, further distortion is used in the Phoenix airport's trial system where photo-quality images are replaced by chalk outlines. The TSA has also commented that screening procedures such as having the screener viewing the image located far away from the person being screened could be a possibility. In light of this, some journalists have expressed concern that this blurring may allow people to carry weapons or certain explosives aboard by attaching the object or substance to their genitals. The British newspaper The Guardian has revealed concern among British officials that the use of such scanners to scan children may be illegal under the Protection of Children Act 1978, which