Buttocks. Some flesh. At least two pairs of legs.

And a student who took pictures of what appears to be a steamy sex act, taking place against a window in a dormitory, clearly visible to any passersby.

Those ingredients are brewing some heated debate over First Amendment protection at the University of Pennsylvania as some recall a 1993 “water buffalo” incident that many thought taught the university to stay away from regulating free expression.

The photographer, an engineering junior, posted the pictures several weeks ago on his password-protected university Web site, which eventually garnered attention at CollegeHumor.com. The pictures are also now widely circulating at Penn.

On Wednesday, Andrew Geier, a psychology graduate student who has served as the photographer’s adviser to the Office of Student Conduct, said that the student has received memos indicating his actions violated Penn’s code of student conduct, sexual harassment policy and policy on acceptable uses of electronic resources. In addition, the documents labeled one of the photographed students an “injured party” who felt “serious distress,” with the situation causing “an intimidating living environment for her.” The photographed students are not identifiable.

The documents, signed by Michele A. Goldfarb, director of the office, indicated that as punishment, the student would face disciplinary probation until graduation and be forced to write essays on conduct and letters of apology to the students he photographed.