QUOTE(Critical_Fallacy @ Jul 16 2013, 06:16 PM)
So, “
what are right actions?” Please enlighten us. The answer to the question probably requires another question: “
What is the right way to be?” Most people would tend to agree that the moral quality or
virtue of the person is fundamental. By considering your moral reasoning, we hope we can
make morally enlightened choices that express our deepest convictions and highest aspirations.

The right way to be, only examiners can examine or assess scripts.
I am more concern on the validity of the marked scripts than the ethics of the supervisor. For example, how can the supervisor (lecturer) ensure that all the markings are done correctly? This can lead to various repercussion if a student who is suppose to fail, get a pass; vice versa. I cannot think of any valid reason to allow or support such arrangement.
Also, since this is a university, I presume that there is a certain level of confidentiality here. By exposing the scripts to a non-faculty member, the supervisor (lecturer) is already breaching rules.
For the sake of discussion, asking your postgraduate student to mark an examination is different from asking him to supervise a research work.