They can, and they do! If a person uses a peer to peer file sharing programs like Bit Torrent or a similar program, law enforcement can, and will, search your computer without your knowledge.
There has been an explosion of child pornography cases, particularly here in Florida. Most of the cases involve a “secret” search of a person’s computer by specially modified law enforcement peer to peer programs like “Bit Torrent LE”
ICAC, a federally funded organization, maintains an “inventory” of known or suspected child porn images or videos, categorizing them by “hash values”. There is another law enforcement application that can track and identify any IP address that receives or transmits an image with a known hash value. Once that IP address is identified, local law enforcement uses their special application to tap into that person’s computer and extract files without their knowledge. That is then followed by a search warrant, a raid, and an interrogation. The search warrant in every instance comes not before but after the secret search. Law enforcement justifies this secret search as “consensual” claiming that if a person uses a file to file sharing program, “they have consented to share”.
I am challenging this “claim” in several of my current child porn cases and the legality is yet to be determined.
Defending child porn cases is a tough uphill battle. The prosecutors go after violators with a vengeance and here in Sarasota and Manatee County routinely file 40 counts, running the guidelines up to 30 years in prison. The challenge is educating the judges and getting people to understand what the police are really doing. The stigma of kiddie porn is such that some people feel the end justifies the means. It is only a matter of time until this practice is exposed and the illegal searches are found to be illegal by the Courts.