How does that deny hard currency to Cuba? Did I, and other adjunct professors who may have been involved, have such reputations as high rollers that U.S. officials believed keeping us off the island was a good way to bring down the Cuban economy? Absurd. So what was the purpose?

Of course, there are no more courses for me to teach in Cuba, even if I wanted to be a full-time member of the faculty. From 1997 until we were prevented from doing so in June 2004, Johns Hopkins had taken to Cuba 15 to 20 students for three weeks every January to focus on some aspect of Cuban society, history or culture. These courses were very popular with our students, especially because they neatly fit between semesters and did not interfere with graduation schedules.

But the new regulations require that the courses be no less than 10 weeks. That would mean spending an extra semester registered at Hopkins and would bar on-time graduation. Our students prefer to graduate, and so, for all practical purposes, Hopkins courses in Cuba have been brought to a halt - as have courses in Cuba organized by most other colleges and universities.

Another provision of the new restrictions is that in order to register for a course given in Cuba, students must be full-time degree candidates at the college or university offering the course. This goes against the traditional practice of allowing students from other institutions to participate in such courses and ended academic consortia that allowed colleges and universities to send students to one another's Cuba programs, thereby greatly reducing the costs and making them accessible to more students.

Why were these restrictions put in place? The first reason put forward by the Treasury Department was "to eliminate a practice [of abusing academic licenses] that was undermining the embargo's purpose of isolating the dictatorship economically."

But the Treasury Department could point to no abuses. No academic travel licenses had been revoked. No academic group had been accused of violating the rules.

One suspects that such "abuses" were nothing more than inventions of the Treasury Department to give fictitious justification to its new restrictions on academic travel.

The second reason for the policy put forward by Treasury officials is even more surreal. It was intended "to promote civil society by continuing to foster free exchange of ideas between American students and professors and members of Cuban society."

Can they be serious? They must have known that the new restrictions would have the opposite effect.

The Supreme Court in various cases has held that an academic institution may, without interference from the government, decide which courses could be taught, how they would be taught, who could take them and who could teach them. The restrictions handed down in 2004 violate all of these.

That is why the Emergency Coalition to Defend Educational Travel, of which I am the chairman, has challenged the legality of these measures. It has just presented its brief to the U.S. District Court for the District of Columbia, pointing out that the restrictions on academic travel initiated in 2004 can only be seen as an assault by the executive branch on the constitutionally protected rights of U.S. citizens. It is an assault that must be turned back.

Wayne S. Smith is an adjunct professor at the Johns Hopkins University and a senior fellow at the Center for International Policy in Washington. His e-mail is wsmith@ciponline.org.