"And we are proposing to the committee that they ought to be, just to insure that the powers are fully spelled out and there is adequate control over those powers."
The existing regime requires much more specific information from agencies applying for a spying warrant, Gwyn said. These details allowed the minister and the commissioner in charge of the agencies to balance the risks and the benefits of the warranted activity.
"We would like to see that .. warranting regime tightened up ... to retain some of the key controls from current legislation," Gwyn said.
Agencies should be able to spell out the type of intelligence they expected to obtain under a warrant, and the type of interception or tracking they would undertake.
She pointed to recent cases in New Zealand and overseas in which spies had sometimes been guilty of "casting about" for a legal basis for their actions after they had carried out surveillance.
"Given the extensive and intrusive powers the agencies have, generally exercised covertly, they should be authorised only when carefully targeted."
The bill will also allow the intelligence agencies to use "purpose-based warrants" which do not target specific individuals or places but only a type of information and the reason why it is required.
It has been proposed that the warrants could be used to intercept the communications of New Zealanders fighting for ISIS overseas, whose identities are not known, or to intercept the communications of a foreign intelligence officer in New Zealand at short notice.
Gywn said either of these tasks could be achieved with a specific warrant.
"I do not therefore see a basis for this new power," she said in her written submission.
"Justifying it requires both an important practical need and a cogent explanation of why the need cannot be otherwise met. The examples given do not establish that need."
