James Murdoch has denied that he tried to use the political influence wielded by his father's newspapers to steer through the largest takeover in his company's history.
Rupert Murdoch's News Corp was forced to abandon its $12bn bid to take full control of pay TV group BSkyB last year.
That move came after revelations that his News of the World tabloid had illegally hacked into phone messages on an industrial scale to obtain scoops.
At a judicial inquiry into press ethics set up after the scandal, Rupert's son James was questioned at length on his handling of the affair and his dealings with the government.
He revealed extremely close ties with the minister responsible for the final decision on the BSkyB takeover, Jeremy Hunt.
He also acknowledged he had discussed plans for the takeover with Prime Minister David Cameron at a private dinner, although he said in general he left politics to his father and their newspaper editors.
The inquiry is looking at ties between politicians and press barons, especially Rupert Murdoch, who has wielded enormous influence for four decades.
At the time the scandal broke last year, the younger Murdoch ran his father's UK newspaper empire and was chairman of BSkyB, where News Corp, the largest shareholder, was seeking government permission to take full control.
The affair has been deeply embarrassing for Mr Cameron, who has faced scrutiny into his close personal friendships with senior News Corp executives and his judgement in naming a former News of the World editor as his spokesman.
Today's questioning revealed close contacts between News Corp and Mr Hunt's media and culture department.
Emails sent between News Corp staff stated that the government minister accepted the strength of their argument and thought it was ''game over'' for rivals who opposed the deal.
Emails sent by a lobbyist for News Corp stated that Mr Hunt "shared our objectives" and one email said he had got hold of some information on what Mr Hunt would say in his statement on the deal, although he added that this was "absolutely illegal".
The government's willingness last year to approve the controversial deal prompted critics to argue that Mr Cameron and Mr Hunt had been too close to the Murdochs.
After the hacking allegations snowballed, Mr Cameron called on News Corp to withdraw the bid, effectively dooming it.
Investigations into the hacking scandal have hinged on how much James Murdoch knew about illegal practices at the News of the World, especially when he approved a large payout for a hacking-related legal claim.
He has consistently maintained that underlings - in particular then-editor Colin Myler and lawyer Tom Crone - failed to alert him to the extent of the wrongdoing.
"Knowing what we know now about the culture at the News of the World ... then it must have been cavalier about risk and that is a matter of huge regret," he told the packed court room.
He said he had not been sufficiently in touch with the culture at the tabloids to question subordinates.
Asked if he even read the News of the World, he said: "I couldn't say I read all of it.
"I wasn't in the business of deciding what to put in the newspapers," he added.