The Prime Minister has highlighted a lack of trust as a major barrier to Government agencies being able to deal with the problem of domestic violence.

Bill English has identified it as a problem as he's opened a Family Violence Summit in Wellington today.

He said a major part of fixing family violence problems is knowing the people you need to change, but currently authorities don't have this information.

"Because why would you tell a government agency or a policeman? They don't trust us, particularly if they're people with a lot of interaction with the government system, so we can't deal with people with whom we have no relationship."

Mr English is questioning the focus of the public service when it comes to handling domestic violence.

He said it's easy, when providing services to dysfunctional families, to create co-dependency - that the public service ends up needing the misery.

"And you can feed off each other. Sometimes on my worst days I think we spend billions servicing misery rather than trying to reduce it."

Justice Minister Amy Adams and Social Development Minister Anne Tolley launched new response guides at the Summit.

In essence they're a framework setting out definitions, protocols for assessing risk, and a consistent approach for supporting victims and perpetrators.

"By working together we stand a much stronger chance of achieving better outcomes for victims and their families," Mrs Tolley said.

Ms Adams said the old approach is too fragmented.

"There are too many doors and paths to navigate so many victims and perpetrators either don't get the right help for their particular need, or don't get any help at all.

"What I believe we want to see is a future system where there is no wrong door," she said.

"No matter who a victim talks to about their experience, that person can find the information about what they need to do to help the victim."

Ms Adams said she's speaking to sector groups in Wellington this morning, in the hope of broadening the discussion and finding out from those on the front line how they believe we can tackle the problem.

"The point we've made continually is that this is not something the Government alone can solve. The Government has to be a big part of it and we want to check that we are on the right track and that our future work programme is calibrated in such a way that the sector sees us making a big difference."