Police get lots of positive publicity for arresting alleged sexual predators caught in online stings. But there are lots of gray areasof the law behind the bright lights. Police sometimes cross the line into entrapment. They also arrest people for online fantasy sex in which in which there is no real victim.
Online participants apparently play roles, including that of juveniles, during these virtual encounters. If the underage virtual partner turns out to be a cop, the other participant ends up in jail.
A common defense in such cases is that the defendant believed the “underage” virtual participant was an adult. That defense hasn’t worked, generally, and those who used it received stiff prison terms. But a new study in Australia suggests that some defendants who say they could tell the underage parter was really adult may be telling to truth.
Forensic psychologist Karen Franklin gives the details here in her always timely blog.
Wrongful Convictions Blog 
Thank you Martin.
I also agree re Ms. Franklin, Ph.D.
I believe her work is excellent.