Judge not, lest ye be a judge...or a law professor. Teaching law comes close to being a judge without a gavel. Professors make up legal disputes for students to argue about called hypotheticals, and they rule and award judicial relief in the form of grades.

The story of the law professor goes way back to ancient Greece. Shortly after Plato had recorded Socrates' immortal last words, "What's in this?" the three followers of the old sage gathered around to read his will.

"If you're reading this, my friends," read the testament, "you now know that, 'All men are mortal, Socrates is a man, therefore, a man, a plan, Panama.' No doubt you're also wondering what to do now that I'm gone. Plato, you were my finest student, so I'm giving you my tenured position as the philosophy chair at the Academy. All you have to do is build the school.

"Crito, we owe a sheep to Asclepius. But since I don't have one and I'm not the kind of guy who times going to the bathroom when the check comes, pay off Asclepius with the 10% off Spartan electrolysis coupon in my robe.

"Finally, not unmindful of you, Prof. Christopher Langdell, I want you to know that I was only hard on you for your own good and that I don't want you to subject your law students to my methods. Instead, give them candy, tuition-free education, straight As, and glowing letters of recommendation for federal clerkships."

The next day, Prof. Langdell went to the law school, placed a sign on the wall of his classroom that read, "No Candy, Clerkships, or Complaining," and taught his students using the Socratic method.

While it's doubtful law professors still have a sign like that, one thing's for sure: Since Prof. Langdell, the way in which law professors use the Socratic method—posing a series of questions to a student who teaches the class with her answers—has defined the law professor as a teacher, inspiration, and drill sergeant for generations of law students.

Law professors, like Socrates before them, love to play the gadfly, and, in a way, it can't be helped. Law students are a talented, studious folk who like to be right. Then comes that first day of law school, when law professors inform them that there are no "right" answers in the law, let alone certainties.

"Yes" is "maybe," "no" is "it depends," and the answer to the question, "What number am I thinking of?" is, "Blue." The fewer "right" answers, the more likely students are to engage legal texts in a way that nurtures the little lawyer inside them.

"That's it? How hard could question-asking be?" you ask. Harder than you think. Knowing what questions to ask in order to explain obscure legal principles is no easy feat, like getting Kanye West to give back the mic. It requires familiarity with the subject's core materials: cases and statutes.

Most professors teach using casebooks, which contain edited and abridged (in the loosest sense of the term) legal materials of an area of law—contracts, torts (not the delicious cake), property, and so forth. The idea is to have the students read the casebook materials, and have the law professor supplement their learning with additional information, which means doing more research than the law students.

But if you've become a law professor, doing more reading and research should come as no surprise from the tiny print of your contract. Law schools pay law professors to research, write, and publish legal articles and books to gain prestige. In fact, some professors take a semester off every now and then to focus just on their research. It's getting harder and harder to persuade a law school committee that there needs to be yet another article written on Fiji beach law based on personal experience.

And at some point towards the end of the semester, law professors and their students have to engage in the ritual of celebration of learning: exams. Exams can be tough on both students and teachers, unless it's Scantron, in which case it's just hard on the students.

Usually, though, law professors require students to write essay exams under severe time constraints. Naturally, this means that grading the strength of an argument can range from Justice John Paul Stevens-quality to Faulknerian, "My essay is a fish," stream of consciousness.

Law professors also have a thing known as "office hours," during which time they serve as career advisors to students. As a rule of thumb, the older the professor, the likelier students' questions might be answered with a "war" story; that is, a story about the days when the professor was a lawyer. "Now let me tell you about my old Victrola...."

• More