Prosecutors were today ordered to take "special care" when trying to get journalists to disclose their sources.
Lawyers must decide if newsgatherers are striking the right balance between public interest and criminality, guidelines from the director of public prosecutions said.
Keir Starmer QC said his new rules would help lawyers with the "very difficult decisions" surrounding Scotland Yard's phone-hacking inquiry.
The report urged caution over attempts lawyers might make to force journalists to reveal the identities of confidential sources.
It also tells prosecutors that deciding if journalists should face court is "not an arithmetical exercise".
The 17-page interim guidance includes details of likely sentences for illegal practices relating to journalism.
Phone-hacking related offences carry jail terms of two years, the report says.
Mr Starmer said: "Freedom of expression and the public right to know about important matters of public debate are an essential foundation of our society - but there are limits for those who cross the line into criminality.
"These guidelines will assist prosecutors in striking the right balance between those interests in cases affecting the media.
"Journalists, and those who work with them, are not afforded special status under the criminal law, but the public interest served by their actions is a relevant factor in deciding whether they should be prosecuted in an individual case."
Mr Starmer added that the rules would have helped lawyers come to swifter conclusions in the past.
He raised allegations against journalists regarding the parliamentary expenses scandal as an example where lawyers were right not to make charges.
Mr Starmer said: "These guidelines will ensure consistency but will also provide openness and transparency to the public on what victims can expect, and to the media on the approach that prosecutors will take when considering such cases.
"This is an issue of great public concern and I want to give everyone who is interested a chance to give their views on what prosecutors will consider."
The report requires prosecutors to consider the European Convention of Human Rights' assertion on the use of confidential sources.
"That does not mean that prosecutions should never be brought where journalists may have to disclose their sources, but it does require prosecutors to give weight to the public interest in protecting journalist' sources when assessing whether the public interest served by the conduct in question outweighs the overall criminality," the guidelines say.