Jay Wilson, a second-year law student at New York University, was desperate to register for a popular course in constitutional law.

Unfortunately for him, the course, taught by the youthful Daryl Levinson, was completely booked for the upcoming spring semester. Fortunately, Mr. Wilson had some money to spare. In a posting on an online bulletin board at the law school, Mr. Wilson offered $300 to any student willing to drop the course to make room for him.

“No responses for Con Law yet,” he later wrote in a posted message obtained by The New York Sun. “Please please. I’m raising the offer for Levinson to $500. Serious offer.” His previous offer apparently went unanswered.

The proposal stunned even the most jaded law students, who are familiar with the lengths to which their classmates will go to have their way. And it angered school officials, who quickly moved to prohibit the buying and selling of course spots on the NYU Web site.

After much debate among members of the student bar association, a compromise was reached: Students may swap courses but may not offer cash or “cash substitutes.”

Students interviewed at the law school said the practice of exchanging course spots is common at the school. As a kind gesture, some cash-strapped students have promised to bake cookies for willing traders or pass them invitations to exclusive parties.

Mr. Wilson, they said, took things to a new level: a no-nonsense business deal, the sort of financial transaction that they expect to deal with only after graduation.

While the idea of parting with half a month’s rent to gain entree to the course in constitutional law struck students as unusual, some said they could understand the rationale.

“If you calculate the cost of financing a legal education at NYU to be around $160,000, what’s another $500?” said Peter Pihos, a third-year law student.

A second-year student, Tamara Katz, said she is opposed to selling a spot in any course, even for more than what Mr. Wilson was offering.

“I think people should not support that,” she said. She argued that if the practice were approved by NYU, then poorer students would be at a disadvantage.

It’s not clear why Mr. Wilson was so bent on registering for constitutional law, a required course that students said is offered in two sections each semester. He was also apparently willing to spend $300 to get into a course on evidence taught by Burt Neuborne, a prominent legal scholar.

After posting a message in which he asked students to name a price and “not be shy,” Mr. Wilson took a more direct approach.

“I haven’t had any response, and I really, really want one of these classes. Both are related to a paper I’m working on,” he wrote. “If you are dropping one of these classes and will give it to me, I will give up some or all of my winter vacation in order to pay for your winter vacation, to donate to a charity of your choice, or anything else you would like. I will start by offering $200 for Evidence, $300 for Con Law.”

No one on the NYU Web site has responded to Mr. Wilson’s offer, students said, though it’s possible that students in those courses may have privately contacted him and accepted his deal. Mr. Wilson could not be reached for comment.

The Web site is called “coarses-list,” an allusion to both the online market Craigslist and a University of Chicago scholar and Nobel Prize winner, Ronald Coase.

Mr. Coase, as a typical NYU law student knows all too well, is best known for his theorem arguing that it doesn’t matter how governments distribute property rights because the free market will ultimately allocate rights with the greatest efficiency.

Some students noted that the theorem ingrained in them at law school would seem to argue against NYU’s prohibition on selling course spots.

As far as an NYU law school vice dean, Barry Adler, was concerned, “Coase’s theorem” was not relevant.

“This practice exploits limitations in the University’s enrollment technology,” Mr. Adler, who teaches at the school, wrote to students in announcing the new policy on Web course-swapping. He said law students have no right to sell spots because the openings are not their “property.”

Students can register online and rank courses they want to take. Through a lottery system, students are registered automatically for courses. Some students have complained that the university doesn’t offer any wait list that would allow students to be placed automatically in their top choices when other students drop out.

Mr. Wilson, however, was unrepentant. After finding out about the ban, he posted: “I thought I would have to wait until working in a ‘real world’ legal job in order to see such abuse of the principles we have been learning here.”