Is it ethical to have a former student serve on my hiring committee at a community college?
Some colleges and universities have students in hiring committees, either as observers, non-voting members, or full members. In the university where I studied, power was shared roughly 40% / 30% / 30% between faculty, staff, and students. Hence it was obvious that there would be student representatives as full voting members in almost every committee.

Individual members of the hiring committee tend to have conflicts of interest with individual applicants, especially because the committee is often selected in advance. When such conflicts occur, the conflicted member should find a way to handle the situation, e.g. by observing the interview instead of actively participating in it.

The situation gets interesting with internal applicants and student representatives, because every potential student representative probably has a conflict of interest. If university regulations state that there must be a student representative, then the student repersentative may have to participate in decisionmaking regardless of conflicts of interest. The relevant principle here is that if every potential representative has a conflict of interest, then no one has.