Police say they are training their staff intensively to help administer laws on search and surveillance which are now in force.
The Search and Surveillance Act which took effect on Monday gives police and other officers powers to search, or keep people under surveillance, without a warrant in situations of emergency or urgency.
Its powers replace those previously spread across 69 pieces of legislation, including the Prostitution Reform, Biosecurity and Dog Control Acts.
The legislation allows more government agencies to carry out surveillance operations, changes the right to silence and allows judges to decide whether journalists can protect their sources.
Police Assistant Commissioner Malcolm Burgess told Morning Report the law change is not a massive increase in the powers of the police, and those which have been granted are commonsense ones.
"We can do some forms of surveillance and some forms of searches without a warrant, in circumstances that are pretty commonsense, they're either emergencies or where the destruction of evidence might occur in very serious cases."
Civil rights lawyer Michael Bott says the legislation extends many police powers to a large number of Government officials.
"The scope for the state to basically surveille citizens has been dramatically increased," he told Nine to Noon.
Mr Bott says officials will now be able to carry out surveillance based on their suspicion of an offence, rather than having reasonable grounds to believe an offence is being planned.
Constitutional law specialist Grant Illingworth, QC, says the courts will have a huge task in interpreting the new law.
He says searches always involve breaches of privacy, but it is not clear that the new legislation strikes the right balance, and determining whether it does will take some time.
Many government agencies, such as the Pork Board and the Inland Revenue Department, already have search and surveillance powers that can be used to check for either compliance or suspected offences. The new laws clarify exactly how those warrants can be obtained, and how a search can be carried out.
The Government says the legislation will be reviewed within the next four years to ensure it is operating effectively, and decide whether it needs any improvements.