A Guardian journalist has told the inquiry into media ethics how he hacked the phone of an arms company executive, but described that act as "perfectly ethical".
Mr Leigh first admitted to hacking the arms executive's phone in an article written afer the phone hacking conviction of News Of The World Royal Editor Clive Goodman in December 2006.
David Leigh, the paper's investigations editor, told the Leveson inquiry: "I don't hack phones normally. I have never done anything like that since and I had never done anything like that before."
The Guardian journalist wrote that he felt a "voyeuristic thrill" listening to the voicemail messages.
In the article, he said: "I too once listened to the mobile phone messages of a corrupt arms company executive - the crime similar to that for which Goodman now faces the prospect of jail."
The inquiry heard how the businessman in question had inadvertently left his voicemail pin code on a computer print out, allowing Mr Leigh to dial straight into his voicemail.
The journalist wrote: "There is certainly a voyeuristic thrill in hearing another person's private messages.
"But unlike Goodman, I was not interested in witless tittle-tattle about the Royal family. I was looking for evidence of bribery and corruption."
"And unlike the News Of The World, I was not paying a private detective to routinely help me with circulation-boosting snippets."
Mr Leigh told the inquiry: "On that particular occasion, this minor incident did seem to me perfectly ethical."
I don't hack phones normally. I have never done anything like that since and I had never done anything like that before.Guardian journalist David Leigh
Lord Justice Leveson also heard from a delivery van driver who said he tried to warn about the potential for voicemail hacking more than 12 years ago.
Steven Nott, from Cwmbran, South Wales, said he discovered how easy it was to access other people's voicemails in 2009 when he needed to pick up messages from customers when Vodafone's network was down.
He was informed by the phone company that he could access his messages by phoning his number and entering a default pin number.
Mr Nott told the hearing: "I thought to myself 'this is insecure' straightway."
The witness said he contacted journalists at the Mirror and the Sun to tell them about the security risk, but they never ran stories.
He said he also contacted the authorities, the police, MI5 and the Home Office but again they never replied to him and did not appear to be interested.