Almost 50 years ago, in April of 1954, Vannevar Bush testified before a government review board in defense of J. Robert Oppenheimer. It was the heyday of McCarthyism, and Oppenheimer, an atomic-bomb pioneer, was being investigated for his opposition to the hydrogen bomb and his alleged left-wing associations. Bush, who had headed virtually all civilian military research during World War II, warned that the hearing ran the danger of “being interpreted as placing a man on trial because he held opinions, which is quite contrary to the American system.” He continued, “If you want to try that case, you can try me. I have expressed strong opinions many times. They have been unpopular opinions at times. When a man is pilloried for doing that, this country is in a severe state. Excuse me, gentlemen, if I become stirred, but I am.”

And excuse me if I am also stirred-by events today. Having great faith in American openness and democracy, I have always found it hard to understand how McCarthyism took hold. Certainly, during my adulthood, this country’s democratic values have been periodically tested. But still I couldn’t see how anything as extreme and widespread as McCarthyist ultranationalism could reappear. After reading “Biotech’s Big Chill,” I am no longer so certain. The story outlines how, in response to terrorism, the United States government is increasing restrictions on foreign students and limiting the access of both foreign and U.S. citizens to various materials and lines of research-mostly biological. While some of these changes are reasonable, I fear that on the whole we are coming perilously close to something similar to McCarthy’s 1950s.

“Biotech’s Big Chill” is written by Daniel J. Kevles, a noted Yale University historian and a contemporary observer of science and technology in society. He is also a member of the Science, Technology, and Law Panel of the National Research Council (the principal operating arm of the National Academy of Sciences and the National Academy of Engineering), which has considered some of the emerging issues in science and national security. Kevles, of course, speaks for himself alone. In his piece, he notes that during the Red Scare scientists came under scrutiny because of past or present political affiliations-and that they could theoretically be cleared of suspicion by repudiating those affiliations or any “dubious” actions. “In contrast,” he writes, “what makes a scientist suspect today is his or her nationality, which is difficult to modify, or ethnicity, which is unchangeable.” Such restrictions, coupled with other new rules and regulations, Kevles concludes, “may pose difficulties for contemporary biology that are far more chilling than those prevailing in early Cold War physics.”

I’m not saying the government is wrong to act. Indeed, some new restrictions-namely, increased controls on biological agents such as Ebola and anthrax-are entirely prudent. But the government has also categorically excluded certain researchers, those coming from nations on its list of state sponsors of terrorism, from working with these agents. That seems both lazy-there are such things as background checks, after all-and undemocratic. And it’s just the edge of the storm cloud looming on the horizon for foreign researchers in this country.

Under the latest controls, all foreign nationals from 25 countries entering the U.S. to study anything, not just biology, must be registered in the government’s new tracking system. Anyone from this list of nations must be fingerprinted, photographed, and interviewed by the immigration service. What’s more, if foreign students stay in the U.S. after graduation, they must be tracked for three years by their alma maters-which must submit regular updates to federal authorities.

Kevles’s article homes in on biology and biotechnology, fields in which foreigners represent a significant portion of the work force-and where the aura of restraint and caution is especially strong. In part because the new climate discourages foreign nationals from working for U.S. firms, and in part because it discourages sharing of information among colleagues, “it could,” Kevles writes, “thus threaten the engineering of therapies and cures and as such place at risk the very competitiveness of the nation’s biotechnology industry.” But the ramifications go far beyond biotechnology. A December 2002 statement by the presidents of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine concludes that constraints on foreign students and visitors in the name of national security have already had “serious unintended consequences for American science, engineering, and medicine.” This important statement cites as evidence of these consequences impaired research collaborations, the prevention or delay of approvals for “outstanding young scientists, engineers, and health researchers” to enter the country, and the hampering of international conferences.

U.S. science and technology, and indeed economic growth, have always benefited from a continual influx of talented foreigners who embrace democratic ideals and opportunities and therefore stay in the country-where they make wonderful contributions. Increasingly, these talented people have many other options in Europe and Asia. Especially if another terrorist event occurs, and we knee-jerk our way to even more restrictions that make them feel like second-class citizens, more will choose not to come, or not to stay-and the nation will suffer. I can just hear Vannevar Bush becoming stirred again.