'Fake Sheikh' Mazher Mahmood: End justifies means
12 December 2011 Last updated at 12:36 GMT
Former News of the World investigations editor Mazher Mahmood, known as the "Fake Sheikh", has given evidence to the Leveson Inquiry into media ethics and standards.
Mr Mahmood, who now works for the Sunday Times, said his undercover work was always in the public interest.
He said the end justified the means and gave an example of how he bought child pornography as part of an investigation which led to a criminal being arrested.