The report singled out Rupert Murdoch's defunct tabloid The News of the World for sharp criticism.
"Too many stories in too many newspapers were the subject of complaints from too many people with too little in the way of titles taking responsibility, or considering the consequences for the individuals involved," the head of the inquiry, Lord Justice Sir Brian Leveson, said in a 46-page summary of the findings in his long-awaited, 1,987-page report published in four volumes.
"The ball moves back into the politicians' court," Sir Brian said, referring to what form new and tighter regulations should take. "They must now decide who guards the guardians."
The report was published after some 337 witnesses testified in person in 9 months of hearings that sought to unravel the close ties between politicians, the press and the police, reaching into what were depicted as an opaque web of links and cross-links within the British elite as well as a catalog of murky and sometimes unlawful practices within the newspaper industry.
"This inquiry has been the most concentrated look at the press this country has ever seen," Sir Brian said after the report was made public.
But in a first reaction, Prime Minister David Cameron resisted the report's recommendation that a new form of press regulation should be underpinned by laws, telling lawmakers that they "should be wary" of "crossing the Rubicon" by enacting legislation with the potential to limit free speech and free expression.
Mr. Cameron's remarks drew immediate criticism from the leader of the Labour opposition, Ed Miliband, who said Sir Brian's proposals should be accepted in their entirety.
Mr. Cameron ordered the Leveson Inquiry in July, 2011, as the phone hacking scandal at The News of the World blossomed into broad public revulsion with reports that the newspaper had ordered the interception of voice mail messages left on the cellphone of Milly Dowler, a British teenager who was abducted in 2002 and later found murdered. Sir Brian said there had been a "failure of management and compliance" at the 168-year-old News of the World, which Mr. Murdoch closed in July, 2011, accusing it of a "general lack of respect for individual privacy and dignity."
"It was said that The News of the World had lost its way in relation to phone hacking," the summary said. "Its casual attitude to privacy and the lip service it paid to consent demonstrated a far more general loss of direction."
Speaking after the report was published, Sir Brian said that while the British press held a "privileged and powerful place in our society," its "responsibilities have simply been ignored."
"A free press in a democracy holds power to account. But, with a few honorable exceptions, the U.K. press has not performed that vital role in the case of its own power."
"The press needs to establish a new regulatory body which is truly independent of industry leaders and of government and politicians," he said. "Guaranteed independence, long-term stability and genuine benefits for the industry cannot be realized without legislation," he said, adding: "This is not and cannot reasonably or fairly be characterized as statutory regulation of the press."
In the body of the exhaustive report, reprising at length the testimony of many of the witnesses who spoke at the hearings, the document discusses press culture and ethics; explores the press's attitude toward the subjects of its stories; and discusses the cozy relationship between the press and the police, and the press and politicians.
The report devotes an entire section to The News of the World. Using a number of case studies that came from the testimony of witnesses, it described a newsroom under immense pressure to bring in stories exclusively and quickly, full of journalists with cavalier and sometimes cruel attitudes toward the privacy and feelings of the people they were covering. Sir Brian said that reporters regularly obtained information illegally about their subjects, harassed and threatened subjects into cooperating, and concealed their identities in pursuit of stories.
Concluding the section on the ethical practices and culture of the news media, Sir Brian said he recognized that "most of what the press does is good journalism free from the sort of vices I have had to address at length." But still, he says, "it is essential that the need for a fresh start in press regulation is fully embraced and a new regime thereafter implemented."
In the current system of self-regulation by a body called the Press Complaints Commission, newspapers effectively regulate themselves. The report urged the creation of a new independent regulatory body with powers to fine offending newspapers up to $1.6 million, made up of people who are not serving editors and should not be either lawmakers or figures from the government.
In the report, the judge wrote that his inquiry panel heard from a variety of witnesses who gave examples of how the press had hacked into their phones, followed them, intruded on their privacy, illegally obtained information like their phone numbers and medical records, and made up stories about them.
The treatment of private individuals who became public figures, like the parents of Madeleine McCann, a toddler who disappeared while on a family vacation in Portugal, and Milly Dowler indicates a "a press indifferent to individual privacy and casual in its approach to truth, even when the stories were potentially extremely damaging for the individuals named."
But he balanced those remarks by saying that the problems described by witnesses at the inquiry were not systemic, but "afflict only a section of the press, and even then not for the majority of the time."
Summarizing the evidence the panel heard at the inquiry, the judge described evidence of "cultural indifference within parts of the press to individual privacy and dignity."
He continued: "The broad theme encompasses evidence that parts of the press have used unethical and or unlawful means to access private information, including phone hacking, e-mail hacking, theft and covert surveillance. It also encompasses evidence that newspapers have published obviously confidential information without any public interest in doing so, have harassed subjects of their stories and their families, have been insensitive in investigating and reporting death and tragedy, and have failed to have regard to the high level of protection appropriate to children."
The publication of the report was closely watched for what it would say about the seemingly intimate relationship between British government figures and the owners of newspapers, particularly Mr. Murdoch, who testified in person at the Leveson inquiry along with his son James.
Sir Brian said the "overwhelming evidence is that relations between politicians and the press on a day-to-day basis are in robust good health and performing the vital public interest functions of a free press in a vigorous democracy."
But, he went on to say that in other respects, "politicians have conducted themselves in relation to the press in ways that have not served the public interest," had risked "becoming vulnerable to influences which are neither known about nor transparent" and had spent too much time cultivating the press to the detriment of their "public duties."
Speaking after the publication of the report, he said senior politicians have accepted that the relationship with the press had been too close. "I agree," he said.
As the inquiry unfolded, some analysts suggested that Mr. Cameron sought to win the editorial support of Mr. Murdoch's newspapers in return for favorable treatment. But, the report said, "the evidence does not, of course, establish anything resembling a 'deal' whereby News International's support was traded for the expectation of policy favors." Referring to the relationship between the police and the press, Sir Brian declared: "I have not seen any evidence to suggest that corruption by the press is a widespread problem in relation to the police."
Much attention was devoted during the months of testimony to text messages, phone calls and social plans made between Prime Minister Cameron and Rebekah Brooks, the former chief executive of News International, the British newspaper subsidiary of Mr. Murdoch's News Corporation.
The Leveson inquiry ran in parallel with police investigations and parliamentary hearings into related issues.
Ms. Brooks, along with Andy Coulson, a former editor of The News of the World and Mr. Cameron's former spokesman, are among several people facing criminal charges relating to phone hacking and corruption of public officials which they are both challenging in court.
The report also cited testimony relating to the thwarted effort by News Corporation last year to assume full control of Britain's main satellite broadcaster, BSkyB, by buying the shares that it did not already own. It said there was "no credible evidence of actual bias" on the part of government minister, Jeremy Hunt, who oversaw the bid.
John F. Burns, Sandy Lark Turner and Sandy Macaskill contributed reporting.