Many if not most law professors write advocacy as opposed to scholarship. The key distinction is whether ahead of time you know what your conclusions are likely to be and whether subtly or with a hammer drive these points home.
In many respects there is very little to separate law professor advocacy scholarship and expert witnesses who are called to testify on behalf of one client or another. When there are differences the expert witnesses come out ahead on the ethics scale. Why are they superior to law professors who write advocacy? Expert witnesses present their version of the truth but almost always face someone who will present the other side. In addition, they know they will be subject to cross examination which includes the possibility of exposing conflicts of interest. Although the truth does not always prevail, it at least has a chance. With the law professor advocate, that is less true.
Perhaps more important is that with expert witnesses the pretense of objectivity — even though it may exist — is dispensed with. Law professors, though, may appear to be objective. In fact, many are on retainer or of counsel to law firms and write so call “friend of the court” (amici) briefs in which they purport to bring their wisdom to bear to one issue or another. Often this includes pleading with other law professors to sign those briefs. In fact, does anyone actually believe they ever take a position in an article or brief without considering the position that most favors the firms paying them. Or does any one think that many do not get their marching orders from their other employers? Finally, does anyone believe this advocacy is not done while on the payroll of tax and tuition payers? In effect, a law school, and those who fund it, end up subsiding one side of a case it knows nothing about.
I have another suggestion that goes back to the ancient history of the regulation of broadcasting. All topics written on by law professors should be publicly announced. When it is advocacy, whether in the guise of scholarship or an amicus brief, those with the opposite position should be given a chance to respond, also on the law school’s dime. It is called the “fairness doctrine.”