When my sister was student teaching, she was a video-taped for evaluation. The camera was in plain sight in the back of the room -- all the students knew it was there and why it was there.
Sis gave an exam and when grading the exams noticed one of the students had copied answers, verbatim, from an another student. She failed the student and then watched to video tape, which clearly showed the cheating behaviour during the exam.
So, here is the sad part. The parents complained that their daughter shouldn't have been failed for cheating -- that their daughter did not cheat, etc. etc. When confronted by the video evidence they threathened to sue the school district, my sister, etc. etc. for invasion of privacy or whatever they think a lawyer would take on.
Fortunately, common sense prevailed and the princiPAL backed up my sister (who is now teaching full-time, btw). Nothing ever came of the parent's complaint. The girl was a little more well behaved after that episode, according to sis.
Tom P.