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Last week, author Doris Lessing was awarded the Nobel Prize for Literature.

The New York Times used the the governments of Rhodesia and South Africa considered Lessing a "prohibited alien" in 1956 for her political views.

But Jameel Jaffer, director of the ÀÏ°ÄÃÅ¿ª½±½á¹û's National Security Program, that Lessing was also kept out of the United States after she joined the Communist Party. She wasn't allowed back into the U.S. until 1969.

The practice of keeping those with unfavorable political leanings out of the country is called "ideological exclusion," and it's still happening today. You can learn more about it by checking out our special interactive feature - which happens to include Lessing - at www.aclu.org/passportflash.