"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."