The Queen's Counsel who conducted the commission inquiry, Christopher Toogood, said Mrs Caulfield, who works in the Mt Albert electorate office, sent the letter to Ms Dalziel for a political purpose.
Electorate workers were "obliged to tread a fine line" between respecting a constituent's interests and protecting MPs, he said.
Ms Dalziel was forced to resign as Immigration Minister after she gave the letter to the media but then lied about how it was made public.
The document, which had a drawing of a guinea-pig on it, listed options to help a 16-year-old Sri Lankan girl and her grandmother fight deportation after their refugee claims failed.
They included lobbying Helen Clark, and the final option said lawyer Carole Curtis would go to the media.
Neither Mrs Caulfield nor Ms Curtis could be contacted last night.
The inquiry did not investigate Ms Dalziel's actions in releasing the letter, but was set up to find out if any Immigration or Parliamentary Service staff had wrongly handled the letter, which could have been considered private.
Mr Toogood reports conflicting stories about how the letter reached the electorate office, and then Ms Dalziel's office, so he does not record definite findings.
But he indicates what he thinks probably happened.
He suggests that despite their denials, the asylum-seekers had asked for the letter to be photocopied by an Immigration Service employee while they were at the Mangere Refugee Resettlement Centre.
It was probably then passed on to women from a lobby group who were visiting the pair at the time.
Telephone records indicate that group may have faxed it to Helen Clark's electorate office.
Seven months later, as the girl fought her deportation through the media, Mrs Caulfield faxed the letter to Ms Dalziel's office. Senior adviser Michael Wilson did not show it to Ms Dalziel, and a few days later, Mrs Caulfield instructed that the letter be resent. Ms Dalziel released it almost immediately.
Mr Wilson would not tell the Herald why he had not passed the fax to Ms Dalziel, or if he had advised her against its public release.
Mr Toogood said Mrs Caulfield justified her actions by saying Ms Curtis had made a political issue of the case by going to National MP Judith Collins.
The report said MPs and electorate workers were not bound by a part of the Privacy Act that says personal information obtained for one purpose should not be used for another. But there were "sound policy reasons" why they should apply that principle in dealings with constituents.
Refugee case
* The Sri Lankan girl and her grandmother came here in 2002 seeking asylum.
* They made two refugee claims but both failed.
* They initially said they were victims fleeing Sri Lanka's civil war.
* Then the girl said she had been raped by relatives.
* After both refugee claims were rejected, Associate Immigration Minister Damien O'Connor refused to use his discretion to let the pair stay.
* They were expelled in February.
* Immigration Minister Lianne Dalziel said they did not deserve "one jot" of public sympathy.
* Ms Dalziel was sacked just days later after leaking their lawyer's letter but lying about it.
* The girl remains in a Colombo convent.
Christopher Toogood QC:
Report for the State Services Commissioner on Inquiry Into Actions of Employees of the Immigration Service and the Parliamentary Service
re leaking of the "guinea pig" letter to the media [PDF]
Herald Feature: Immigration
Related information and links
