Provide a facility to require that the student acknowledges a "boiler plate" text screen before submitting each assignment. This is likely to be along the lines of reminding them of the rules on plagiarism or suchlike.

One important feature is that the text is reasonably immutable, to avoid a defense of "It didn't say that when I agreed to it".

Discussion:
http://moodle.org/mod/forum/discuss.php?d=97550