After more than three years of being denied entry to the United States for political reasons, the South African scholar and political commentator Adam Habib seemed delighted on Tuesday to be able to plant his feet on sacred ground for America's civil libertarians: the campus of Thomas Jefferson's University of Virginia.

In an interview with The Chronicle, Mr. Habib, who is in the United States on a 19-day tour that will take him to several college campuses, expressed gratitude for Secretary of State Hillary Rodham Clinton's recent reversal of the Bush administration's decision to block him from entering the country. But, Mr. Habib argued, the Obama administration needs to do more than simply grant visas, on a case-by-case basis, to scholars who previously were barred because of their political views or associations. The Obama administration, he said, should put an end to the Bush-administration policy, which kept such scholars out in the first place, known as ideological exclusion....

Mr. Habib, a vocal critic of the Iraq war and some U.S. antiterrorism policies, had been told that the Bush administration's decision to bar him had been based on his role in "terrorist activities." He never learned the charges against him or the evidence behind them, however. Secretary Clinton's order did little to clear up the mystery surrounding his exclusion; it said only that he would no longer be excluded for "any or all acts supporting the denial of his 2007 visa application," without stating what those alleged acts were.

The American Association of University Professors, the American Sociological Association, and the American Civil Liberties Union had banded together with other groups in 2007 to file a lawsuit challenging Mr. Habib's exclusion. The publicity surrounding his case appears to have helped him continue to travel around the world, he said on Tuesday, rattling off a long list of nations in Africa, Asia, Europe, and Central and South America that he visited despite being labeled a terrorist by the United States. Among other scholars who were similarly barred, "I know other people who were not as lucky, who were severely impacted by these labels" and hindered in their travel plans, Mr. Habib said....