For a long time, users have requested the ability for instructors and TAs to submit to the courses they are staffing. This is now directly supported for course uploads via the submit tab.

For a long time, we just used the work-around of enrolling instructors and TAs as students in their own courses. Then, while revamping the external submission engine support last year, I extended it so that course staff could make submissions to assignments that were not yet published or that were already past due. However, if you logged in through the web, course staff could only select courses they were also students in when uploading new submissions. I finally fixed the course selection page so that course staff can select courses they are working on, not just courses they are students in. This works for both the Submit and Results tabs.