It is almost 800 years since the Magna Carta was signed as a constraint against the unfettered power of King John of England in favour of his subjects' freedoms.
Foremost in this document, originally issued in 1215, was the writ of habeas corpus - allowing appeal against imprisonment - but it also evolved the principle of trial by jury and freedom from arrest without a proper warrant.
The original "treaty" was revised many times over, sections rewritten into law during the ensuing centuries, and others repealed, but the essential freedoms it envisaged were safeguarded, finessed and mostly enhanced.
The trend, at least in Western liberal democracies, has been towards increasing protections for the rights of citizens, as can be seen in the Bill of Rights-type legislation most such countries subscribe to.
Occasionally there are, or have been, reverses, most commonly in times of war or when the perceived threats to the State - and all its people - can be argued to outweigh certain rights of the individual.
The furore against the Patriot Act with its wiretapping provisions in the United States, promoted as part on the "war on terror", could be said to be one such recent example; and, the extension of the period of detention without charge to 42 days under Britain's Terror Act, another.
When British MPs voted in June this year on the extension, long-time Labour MP Tony Benn declared it the "day the Magna Carta was repealed".
The tabling this month in the New Zealand Parliament of the Search and Surveillance Powers Bill hardly falls into this category, but raises questions nonetheless.
It has its genesis in a report from the Law Commission five years in the making and is largely, we are informed, a "tidying up" exercise.
"There are many problems with the existing law, with core police powers, many enacted more than 50 years ago, scattered around the statute book," said Justice Minister Annette King.
The law, she said, had among other things, failed to keep pace with technology.
In response, Ms King and the Law Commission proposed a codification of the powers of the police and other enforcement officers "designed to strike a balance between facilitating effective law enforcement and protecting individual freedoms through strict controls and procedural requirements".
Specifically, the Bill proposes that search warrants be able to be obtained electronically or verbally in urgent situations; police being able to search without a warrant if they think there is evidence for a serious crime, punishable by 14 years' jail or more; police being able to detain a person at a place where a search is being done; powers to process documents, take photographs and recordings during searches; and powers to access computer material remotely.
While much of this might seem like common sense in the electronic age, the bypassing of the judiciary whose assent has been traditionally required in the issuing of warrants is a radical step.
Opponents and civil rights groups have already asserted the new laws would give police powers to undertake "fishing expeditions", and say they will significantly dilute the presumption of innocence.
Oral applications could lead to an abuse of powers through the introduction of errors in the process, or simply allow surveillance and search operations to proceed unchecked.
For the most part, New Zealanders can have confidence in its police force.
But it is not beyond reproach.
The most effective guarantee of confidence in state agencies - including the police - is the "separation of powers": the co-existence of independent arms of the state that can act as restraints on each other's power.
Here it is proposed that powers of surveillance and search be "streamlined" and liberalised to the point there is no external "quality control".
On the one hand, the police must be able to act quickly and effectively to combat crime in this electronic age.
But they must also work within defined parameters.
Freedoms acquired over centuries can be jettisoned in a trice if great care is not taken in the devising and drafting of new legislation.
The nature and extent of the parameters in the proposed Bill - and how they would work in practice - are as yet unclear.
This is cause for some uneasiness.
