The Resident Doctors Association is defending its voting practices from criticism by district health boards, which are trying to prevent a new strike.
The union intends to strike for 48 hours starting at 7am on Wednesday, November 23, following a 48-hour walk-out last month over rosters and pay.
The 20 DHBs' bid for an injunction to stop the strike will be heard in the Employment Court at Wellington next Thursday.
The union's national secretary, Deborah Powell, tonight rejected the DHBs' concern over its inclusion of medical students in its strike ballot.
"These are the graduating doctors - trainee interns - who have been employed under this multi-employer collective agreement.
"They have as much interest, possibly more, in ensuring safer rosters as they start their careers as their more experienced RMO [resident medical officer] colleagues do.
"Over 90 per cent of the trainee interns are [association] members, they have been actively following this dispute and are now just as actively participating in decision-making alongside their RMO colleagues.
"I am not sure how the DHBs think that is undemocratic."
Powell also dismissed the DHBs' concern that the strike would make the new-graduate doctors miss their orientation sessions at DHBs.
"One DHB has already shifted the orientation to other days of the week and re-organising sessions such as 'hand-washing', smoking-cessation advice' and 'fire-safety training' which the trainee interns already know about, to another time won't be a problem."
The DHBs' spokeswoman, Julie Patterson, said they were concerned the union held only a national strike ballot, rather than conducting one at each DHB.
Powell said this was a legal question and the union disagreed with the DHBs.
"But in the context of our national multi-employer collective agreement, all voting is nationally based, from ratification to variation procedures."