A review of Government Communications Security Bureau operations has found that three cases identified as having potential legal issues were within the law.
Those cases came to light after the spy agency was found to have breached the law during its surveillance operation of internet entrepreneur Kim Dotcom while assisting police.
The breach in the Dotcom operation occurred because the law governing GCSB prohibits it from spying on permanent residents.
As a result, all 58 cases where the agency had assisted law enforcement agencies from 2009 were referred to the Inspector General of Security and Intelligence.
He has found the law was not breached in any of the operations, including the three in question.
GCSB director Ian Fletcher said on Thursday it has been a thorough process in which the agency conducted an audit, responded to queries from the Inspector General and provided him with classified information.