The bill will expand the powers of the Government Communications Security Bureau to spy on New Zealanders - under an expansion of its cyber security role - and legalises its traditional practice of spying on New Zealanders under authorised warrants to assist the SIS and police.
Mr Finlayson and Mr Key have stated publicly that metadata is classed as communication and therefore cannot be collected on New Zealanders without a warrant.
The committee stage debate will continue tomorrow and the bill won't pass its third reading until at least August 20.
Greens co-leader Russel Norman last night moved amendments, including preventing overseas use of intelligence gathered on New Zealanders.
He also wanted to prevent the GCSB helping the SIS, police or Defence Force to spy on New Zealanders, saying it was never the intention of the current law.
Mr Finlayson effectively acknowledged that the spying done previously to help the agencies had been unlawful.
But he said it had been the intention of the current law but that had been sloppily worded.
United Future leader Peter Dunne has the numbers to pass a series of amendments to strengthen transparency over any spying on New Zealanders, and agreement for a review of spy agencies in 2015 and every five years thereafter.
Act leader John Banks secured the addition of a set of principles in the bill, modelled on those in the Security Intelligence Service Act.
The Law Society, an early critic of the bill, does not believe the changes go far enough. It also criticised the fact that the amendments proposed to the bill by Mr Dunne were made available only yesterday.
The changes did not address the fundamental flaws in the bill and the legislation should not proceed, said the convener of the New Zealand Law Society's rule of law committee, Austin Forbes, QC.
"While the idea of a set of guiding principles is potentially a step in the right direction, the Law Society is not convinced that the proposed wording of the principles provides adequate or effective safeguards," Mr Forbes said.
The use of supplementary order paper procedure to make Mr Dunne's changes without making the details available until today reflected unnecessary urgency.
"This is in the face of mounting public concern and a denial of adequate public debate over the potential loss of personal and data privacy and increased levels of surveillance of both communications and metadata," Mr Forbes said.
Mr Finlayson said members of the legal profession had contacted him with concerns about the Law Society's submission.