I have seen this on a few other weblogs, but felt it so absurd that I decided to bring it to the attention of Tinotopia’s vast audience. At UNLV, relationships between professors and students are not allowed, because:

While consensual relationships may not always be unethical, they almost always cause problems. Some of these problems are as follows:

• they often involve one person exerting power over another;
• seduction of a much younger person, rather than genuine consent, may be involved; […]
• the potential for abuse and exploitation is high;
• the potential for retaliatory harassment is strong when the affair ends […]

Gosh. Well, I suppose that there’s something to that. A student-professor relationship certainly has the potential to be exploitative and will almost always be a pretty unequal one in terms of power. And the UNLV policy only applies to relationships between a professor (or administrator, or anyone else) and a student or other person whose work they supervise. But:

When a romantic or sexual relationship exists, both parties involved may be subject to disciplinary action. Both parties are equally responsible for reporting the existence of the relationship to the appropriate supervisor at the beginning of the relationship.

(Emphasis added by Tino.)

Look; either the student is vulnerable and has to be protected, or the student is “responsible” and the university should get out of the way. You can’t prohibit an activity based on someone’s inability to take care of him- or herself, and then punish the same person for failing to act responsibly in the same matter.