The Independent on Sunday will not face action over the decision to publish a story about Andy Coulson that contained details from his witness statement to the Leveson Inquiry.
Lord Justice Leveson has ordered that no witness statements or document should be made public until they have been given in evidence at the inquiry.
The story was published on May 6 and included details that appeared in Mr Coulson's statement, before his appearance at the inquiry into press standards last Thursday, breaching the order.
Lord Justice Leveson said today that a "detailed ruling" would be published on the inquiry's website, but he would not take action under the Electronic Communications Act.
He said: "I don't intend to take any action under Section 36 of the 2005 Act in relation to this matter but the ruling contains very detailed consideration of the circumstances and I strongly advise anyone who publishes material likely to emanate from our Lextranet system to read that judgment with care whether they be a core participant or not."
Editor John Mullin apologised for the inconvenience to the inquiry last week, but stood by his decision to publish the story, revealing that Mr Coulson held News Corp shares while he was Mr Cameron's head of communications at a time when the Government was deciding whether to approve the company's takeover of BSkyB.
But Mr Mullin told the inquiry that they already had the story "copper-bottomed" from three other sources before he was shown Mr Coulson's statement.
He said: "Nothing that appeared in our story did not come from the three sources that I have underlined."
In a written statement released on Thursday, he added: "As editor, I took the view that the information that Mr Coulson had a potential conflict of interest between his shareholding and his position as an advisor to the Prime Minister was of public interest."