<ol>
<li><p>I know a case where the answer book to a freshman STEM class was in the possession of the students and passed on from year to year. Not uncommon situation I suspect.</p></li>
<li><p>Used to be that frats would have a stash of old tests/lab write ups etc for members to use as needed.</p></li>
<li><p>I adjuncted for a month for a college class. On the test, there were 3 clear cases of cheating (copying answers) involving 8 students (37 total in class). I passed on the evidence to the main prof. I doubt he did anything with it other than tell the students not to do it in the future.</p></li>
</ol>