There are restrictions on the publication of criminals' details
Police forces that "name and shame" criminals must remove the details from websites after a month, new rules say.
Criminals' details such as name, age, where they are from and their offence, should be published routinely on police websites, the Ministry of Justice said.
But data protection and human rights laws mean there are restrictions on what is published, for how long and whether suspects' photos are published.
The new rules will not apply to media websites' reporting of court cases.
The rules state there should be a "presumption" in favour of making information from crown and magistrates' courts public.
Under the rules, officers will also need a specific reason to publish photographs.
The guidance says police and town halls should take into account the impact on the offenders' family of such material and should also consider whether it is "proportionate" to make the verdicts and sentences public.
It also states they should examine whether publishing personal details could have an "unjustifiably adverse effect" on the criminal.
Concerns over the long-term "adverse consequences" for criminals may mean that information is published only on websites linked to the area where the crime was committed.
Websites can also consider saying just that "someone" has been convicted of a crime without revealing the specific details of who, if that is enough to reassure the public.
And the guidance says forces can hand out leaflets or make information available at public meetings instead of putting it on the internet.
"Online publicity needs to be justified, and will not usually be appropriate for minor offences/sentences or for first time offenders," the document states.
However, these rules do not apply to media outlets, such as newspaper websites.
A Ministry of Justice spokeswoman said: "Information about convictions and sentences handed down to criminals is already a matter of public record and widely reported by the media.
"There should be a presumption in favour of publicising these outcomes. Doing so will not contravene the Data Protection Act or breach Human Rights in the vast majority of cases."
Barrister Timothy Pitt-Payne said the rules distinguished between the police and media outlets for a number of reasons.
He said the guidance was meant to deal with concerns there could be breaches of the Data Protection Act 1998 and the right to respect for private life, under article eight of the European Convention on Human Rights, by authorities when they released information.
Mr Pitt-Payne said: "The Ministry of Justice has a role in providing guidance to the criminal justice services, whereas it would expect media organisations to take their own legal advice".
"It isn't their job to give legal advice to the media. In any event different legal considerations would apply in relation to publication by the media and by police or local authorities," he said.
Earlier, Justice Secretary Jack Straw explained the thinking behind the guidelines.
He said: "Individual crimes often get a lot of media coverage and news can spread across communities quickly that a crime has been committed.
"However, the news that someone has been caught, prosecuted, convicted and sentenced does not travel as far.
"This guidance explains, once and for all, that authorities can publish the details of crimes and the punishments criminals have received, and that the government actively encourages them to do so.
"It is vital people know that criminals will not escape the consequences of their crimes."