The judges said in their finding there must be a "de minimis defence'' available for people such as MPs whereby gifts of token value - such as a rugby jersey - were acceptable.
However, the services Field had received were worth about $50,000, and that could not be considered de minimis.
"While we are satisfied that the acceptance of gifts which are de minimis should not be considered corrupt ... the acceptance of other benefits in connection with official actions is rightly regarded as corrupt irrespective of whether there was an antecedent promise or bargain,'' they said.
"In the present circumstances, given the substantial nature of the benefits, no such defence was tenable.''
While in prison, Field worked in the corrections inmate employment (CIE) internal and external grounds parties.
He fitted in well and was "always courteous and respectful towards others in the work parties'' and was an "excellent worker'', his instructor told the Parole Board.
He also gained 17 unit standards in grounds maintenance during his two-year term, as well as six unit standards in catering and a National Certificate in Horticulture qualification.
Field was assessed as being at a low risk of reoffending, with no rehabilitative needs identified.
Outside prison last week, Field said: "Despite what's happened my conscience is clear. I never have at any time had the intention to break any law and, in God's good time, I believe that the full truth of things will be revealed and exposed.''
Field said he had done what all New Zealanders did - paid tradesmen what they told him to pay, Maori Television's Native Affairs programme reported.
``I was a very busy politician and because of the language problems I should have been more attentive to those people and what they did in terms of the minor, not major, jobs that we asked them to do,'' he said.
``Most New Zealanders don't stand around and look at a tradesman doing his job, they just pay what they're told to pay. I should have insisted on invoices and that sort of thing but these people had a language problem, they can't read that sort of thing, can't write.'' Field, an MP for 12 years, and was the first MP to be jailed for bribery, corruption and perverting the course of justice.
