Imran has stated many times that he will not contest any election until and unless an independent judiciary is reinstated. The former Chief Justice of the Supreme Court and eight other Supreme Court justices who were sacked November 3rd, when President Musharraf declared a state of emergency are still under house arrest, more than three months later.
Imran has described the politicians who have chosen to run in the upcoming election as lending legitimacy to what is an entirely illegitimate situation, and it's tough to argue with him.
Without an independent judiciary to enforce the laws fairly, there's no possibility of democracy -- especially in a country that's ruled by a dictator who took control in a military coup. And he makes this point more clearly than any other political leader in the country.
No wonder they don't want him speaking in Karachi!
For more details, here's AFP via Google:
Pakistani authorities barred opposition politician Imran Khan from entering the southern city of Karachi on Thursday because he has called for a boycott of upcoming elections, officials said.
Former cricket legend Khan was put back on a plane to Islamabad after officials prevented him from entering the southern province of Sindh, of which Karachi is the capital, Sindh home minister Akhtar Zamin said.
"We do not want anything to disrupt the elections that is why have sent him back," Zamin told AFP.
"If he does not want to contest elections, it is fine, but he should not incite other people to do so. He will be welcome to visit Sindh after elections."
Khan, a former member of parliament and the chief of the small Movement for Justice party, has called for the boycott of general elections on February 18, saying fair and free polls were not possible under President Pervez Musharraf.
"It is for the third time that Imran Khan had been externed from Karachi and it is highly condemnable," Khan's party secretary general Arif Alvi told AFP.
"It is a violation of constitutional rights of a citizen to move freely in the country and government is doing this because it is afraid the charismatic personality of Imran Khan could create problems for Musharraf."
A coalition of parties, including Khan's, is boycotting the election in protest at ex-general Musharraf sacking top judges under a state of emergency in November.
Khan was held under anti-terror legislation for several days in November.