He pleaded guilty in January and was sentenced in April to 10 months' home detention.
His practising certificate expired in April, but is still listed as active by the Teachers Council.
Parata said their inclusion on the register was a triumph of bureaucracy over common sense.
The news has surprised and angered those in the school community.
The Teachers Council maintains the register of teachers, which notes any disciplinary action taken. Teachers seriously sanctioned remain on the register with the words "cancelled" and "censured" beside their names - but not Parker, Loader and Martin. They are listed as having full registration. The council's director, Peter Lind, is overseas and didn't comment, but a spokesman said it took time and "due process" for teachers to be deregistered.
It is more than a year since Parker's August 2012 guilty plea to offending against boys, and three weeks have passed since he was sentenced to preventive detention on 74 sex charges.
The Teachers Council's complaints assessment committee waited until Parker's sentencing notes were available before referring him to the Teachers Disciplinary Tribunal, which has the power to cancel his registration - but hasn't yet acted.
Manager of teacher practice Andrew Greig said: "It is important that due process is followed and that natural justice occurs, which is why these processes do take time."
Only the Disciplinary Tribunal can remove a teacher from the register, and only once the complaints assessment committee has investigated.
Greig said Parker was referred to the tribunal as soon as his sentencing notes were available. "Because the tribunal is able to use the sentencing notes and witness statements as evidence, it means that witnesses do not have to be called before the tribunal.
In the Far North, Te Runanga-a-Iwi o Ngati Kahu chief executive Anahera Herbert-Graves reacted angrily to the news James Parker was still a registered teacher. "You're kidding? What bastards. Honestly, I just don't know where the hell their heads are."
Post Primary Teachers Association president Angela Roberts said parts of the discipline and deregistration process "absolutely" needed refinement. "'If somebody pleads guilty there should be a fast-track process."
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