As Chill noted, labor lawyers primarily deal with unions. The herd is thinning, but we’re not extinct yet.

An employment lawyer is who you need, and one that specializes in higher education law.

Since your fiancée works for a private university, and not a public school, there is no property right to continued employment, which makes it tougher.

You said having associate professors on the committee was “policy.” Is that actually spelled out somewhere or was it just a practice that has since been altered? If it was spelled out, does the dean have the right to alter policy? Even if it was written somewhere and not altered, the policy wasn’t between your fiancée and the school, so you’d have to assert some sort of third party beneficiary theory.

Why did the dean exclude associate professors? Was there a legitimate business reason or was it designed to make it easier to reject candidates for tenure?

Don’t know if the consequence of not being tenured is job loss or continued employment as a non-tenured professor. If it’s the former, it may make your fiancée more sympathetic in the eyes of the court.

Find a qualified lawyer, one who knows employment law and higher education law. Good luck.