The government has been cleared of any "dishonourable, underhand or duplicitous" strategy in the leaking of Dr David Kelly's name to the press.
Tony Blair: Off the hook
Lord Hutton said he accepted Tony Blair's claim that it would not have been a "practical possibility" to have kept the scientist's identity secret.
But he said the MoD had failed to take "proper steps" to help Dr Kelly in the difficult position he found himself.
He made the assertions as he outlined his report into Dr Kelly's death.
Cover up charge
Lord Hutton said he was satisfied Dr Kelly had killed himself after being named as the suspected source of BBC reporter Andrew Gilligan's controversial weapons dossier story.
The law lord said he did not believe the prime minister or his officials had embarked on an underhand strategy to allow Dr Kelly's name to be made public as Mr Gilligan's source.
Lord Hutton was referring to the 8 July 2003 statement released by the Ministry of Defence which stated that a civil servant had come forward to say he had spoken to Mr Gilligan.
He said if a statement like this had not been issued, "the government would have been faced with a serious charge of a cover up".
Lord Hutton insisted that it had not been an underhand or duplicitous strategy to leak Dr Kelly's name in a covert way.
He said there had been intense media interest in the identity of Mr Gilligan's source.
"It was unrealistic to think the name could have been kept secret indefinitely by the Ministry of Defence," he said.
He continued: "Having considered a large volume of evidence, I consider there was no dishonest, underhand or duplicitous strategy applied by the prime minister or his officials.
"The purpose of the prime minister and his officials to release the statement was to protect the government from a charge of cover up and withholding information important for the Foreign Affairs Select Committee."
He added: "Whatever may be the position in other cases, I think in this case it 's recognised for the MoD that because Dr Kelly's name was bound to come out it was better to be frank with the press and confirm the correct name if it was given."
Lord Hutton said the MoD had also been concerned that no other names of civil servants should be used in the media.
The change in the question and answer brief given to the MoD press office, from refusing to confirm Dr Kelly's identity to revealing it if the correct name was offered, was not a deliberate strategy to name the scientist, he said.
But Lord Hutton said the MoD was "at fault and is to be criticised" for not informing Dr Kelly that its press office would confirm his name if a journalist suggested it.
It must have been a shock and very upsetting for the scientist to discover in a brief phone call from his line manager that a press officer in his own department had confirmed his name to the media.
Lord Hutton said MoD officials had tried to help and support him and Dr Kelly's exposure to the press was only one factor which contributed to him being placed under great stress.
"Because of his intensely private nature, Dr Kelly was not an easy man to help or to whom to give advice," the law lord said.