Pedophiles and child pornographers are increasingly using the Internet to victimize minors. Of the estimated 28 million American children who use the Internet, nearly one out of five say they have been sexually harassed or solicited while online, usually in Internet chat rooms or via instant messaging and e-mail. Last year, the FBI opened more than 1,500 cases involving Internet child sexual exploitation, compared with only 113 cases in 1996. Law-enforcement agencies say it is difficult to investigate and prosecute Web-based sex crimes against minors due to aggressive defense tactics, a dearth of computer forensic specialists and other resources, poorly designed laws and a reluctance by some judges to treat crimes against children seriously. Meanwhile, civil libertarians worry that police “sting” operations entrap otherwise law-abiding citizens.