Preventing leaking exam papers/cheating using phone cameras? I work at an educational institution where exam papers are considered protected. Leaking the exam question sheet and taking photocopies or camera shots is considered illegal and is strictly prohibited. I am not here to argue about this policy but to ask about the best ways to enforce it. Students have been taking pictures of exam papers during exam time, leaking them to subsequent sessions or posting them with solutions and often selling them to students of subsequent semesters. Though we don't use the same questions between semesters, they do exhibit some similarities at times for some courses. 

Even with strict invigilation and requests not to bring cell phones to the exam room, there have been some incidents. Lockers are out of the question, as is collecting all cell phones before exam time. I would welcome any suggestions.
This is not the answer you want but I have to get it out of my chest. (My background is engineering).

The best, most effective and easiest way to completely avoid students taking pictures of exams, selling them and making a profit out of that is:

Publish online all previous exams as an exercise book.

The questions in an exam and the exercises done before the exam should not be more different than an exam and a previous exam, actually old exams make for perfect exercises and practice.

The point is that studying the courses and making a few exams/exercises to practice should be easier and lead to greater success than checking the whole compilation of past exams, which should anyway lead to a good knowledge of the contents of the course (in a more tedious way than reading the theory and checking this with a few exams).

Personal story: When I was in high-school the homework would be much harder than the exams, anyone making the homework (optional) would get good qualifications and the qualifications would reflect actual good knowledge about the subject. In the university there were exercises, but they were explanatory and very basic, the questions in the exam were much harder. This made the exercises useless, students needed exams from previous years just to practice in answering the questions, and I hated that.