The Labour Party is warning proposed changes to the Coroners Act would prevent investigation of the deaths of soldiers killed in action.
Information released under the Official Information Act shows proposed changes would prevent coroners investigating deaths of members of the armed forces killed on operational service or as a result of hostile action.
However, they could still do so if directed by the Attorney-General.
Labour's defence spokesperson, Phil Goff, said he believed this was a way of shutting down criticism of Government and Defence Force decisions and mistakes.
He said should soldiers die overseas, their families needed to know that proper and independent scrutiny would take place.
"The cynic would say that the intention was that they did not want independent scrutiny of actions by a government or by the defence force hierarchy that might be embarrassing to either group.
"I don't think the legislation is necessary and I think we will be worse off because of it."
Mr Goff said changing the Coroner's Act was worrying for the families of New Zealanders killed in hostile action, and would remove any independent scrutiny of such deaths.
"Soldiers' families have always been keen to have independent civilian scrutiny over decisions or analysis that are done by a military court of enquiry.
"They like to have someone there that is outside the military structure and can say things that perhaps the military itself would be constrained to do."
A spokeswoman for Justice Minister Amy Adams said as the bill was before a select committee it was not appropriate for the minister to comment.
The committee is due to report on the Coroners Amendment Bill in August.