Your parent said nothing about a specific law. They're talking about the practice of law. But let's turn that around. If this is a conflict of interest, can you identify for us where that is codified?
(I am not a lawyer and I do not play one on the Internet) lets say it is important to notice this is a State-funded school, the students are adults and the Faculty have long and detailed legal protections in law, in addition to Constitutional rights as individuals.
yes, as noted, the legal framework of law in the USA