A Botswana court has rejected an appeal by an Australian political science lecturer against a deportation order.
Kenneth Good has lived in Botswana for many years
President Festus Mogae declared Kenneth Good an unwanted immigrant in February after he said in a lecture that Botswana was run by a secretive elite.
Mr Good, 72, was led away from the court by plainclothes police and put on a plane to South Africa.
A BBC correspondent says the case casts a shadow over Botswana's reputation as a model African democracy.
"I did not anticipate this kind of judgement. I still believe I did nothing wrong and I did not deserve this," Mr Good told reporters outside the court.
He said he would eventually either return to Australia or go to the UK. He has been a lecturer at the University of Botswana for more than 15 years.
The deportation order had been stayed pending the appeal.
In his academic paper, Mr Good told a packed university lecture theatre that Botswana was run by an elite that made decisions, particularly on the presidential succession, behind closed doors, and manipulated state media.
Reuters news agency reports that the lecture has been widely circulated in Botswana by e-mail.
The BBC's Letlhogile Lucas in the capital, Gaborone, says Botswana's democracy has for many years been associated with free speech.
But this is not the first time that presidential powers have been used in the country to declare a foreigner an illegal immigrant.
Usually, he says, people are declared unwanted in Botswana either if they too vocal or if they are perceived to be security threats.
Mr Good has lived and worked in the country for many years, writing articles that have, on occasion, been critical of government policy.
Reuters said Mr Good was expelled in 1973 by the white minority government in neighbouring Zimbabwe, when it was called Rhodesia.