Hypothetically speaking, could a private university in the USA not prohibit consensual sexual relations between students and faculty because their policy did not include it or the wording in said policy was poor or unclear?
My novice understanding is that private universities have more leeway when it comes to their rules and several ethical subjects seem to be enforced through 'contract law' based on their own policies.
The only time that this conduct has to be prohibited in a private university is when state or federal law prohibits it in any case. In those circumstances, no separate university policy to restate the applicable law is required.
Best practices are to make students and teachers aware of any applicable laws, because knowing that, the the parties are less likely to be involved in illegal conduct. But private universities aren't required to adopt policies of that type if they aren't bothered to do so.
With federal grant funding, private universities are required to have a mechanism in place for addressing sex discrimination complaints, but the policy doesn't have to articulate that particular conduct is or is not prohibited, beyond what federal law provides in the absence of a formally adopted policy.
Incidentally, a few private colleges, almost all religious, specifically decline federal funding in order to be free of the regulations and strings that come with accepting it.
Also, while private universities are not required to have such policies legally, private universities are required, as a matter of practical reality (e.g. in order to be considered eligible to borrow money from banks and to be eligible for many charitable grants) to have liability insurance in place, and liability insurers will often insist that their insured have certain policies in place, especially if the insured private university has a history of prior claims of this type.
As the answer by ohwilleke correctly says, a university is not legally required to have or enforce any policy on this subject.
However, a university may, if it chooses, prohibit romantic or sexual involvement between faculty and current students. I believe that some universities and colleges have such policies, and that at one time almost all such institutions did.
I am confident that the is no US federal law that forbids such a policy, and I very much doubt if any US state has a law that forbids such a policy either. The potential for harassment, favoritism, and other abuse is so obvious, that such a policy would be quite reasonable.
In any case, an employer may have almost any policy it wishes on any subject, as long as it does not violate anti-discrimination law, or laws governing conditions of employment, such as the federal Occupational Health and Safety act. If the employee has a contract, as many faculty do, such a provision would need to be incorporated into the contract or at least permitted by the terms of the contract. If the employee is unionized, such a policy would need to be permitted by the tems of the union contract, and would probably be subject to union contract negotiations. But a policy against student/faculty romances is likely to be accepted (although not required) in any of these cases.
I know that many corporate employers have policies prohibiting romantic or sexual relationships between co-workers, and other prohibit such relationships when one person reports to the other.
There is, of course, an inherent power inequality between a student and a faculty member.
