NOT illegal (Score 1)

Because of the ethical issues associated with deception, Jagatic and Johnson had to obtain permission from the Human Subjects Committee, which approves experiments on campus that involve humans and ensures studies are ethical and do not violate participants' privacy

These guys were given permission to do the study by the Human Subjects Committee. What they did WAS legal, and they CANNOT be prosecuted for it.

You might say that the Committee did something wrong, but not the students.