Disquiet in $1 million meth case follows judgment against police over 2005 P lab raid.
A senior police officer who led a raid criticised as "consciously reckless" by a judge has previously had evidence from another drug bust thrown out in similar circumstances.
On Tuesday, the Herald revealed that evidence in a 2009 bust led by Senior Sergeant Rod Carpinter was dismissed and as a result, two men caught with more than $1 million worth of class-A drugs escaped charges.
In 2005, Mr Carpinter led a search that found equipment and materials used to manufacture methamphetamine at a Huntly address.
But a judge found Mr Carpinter's actions to be "unreasonable as well as unlawful" and the accused walked free.
Justice Rodney Hansen ruled there was "force in the submission" that Mr Carpinter knew searches of the Huntly property were unlawful, yet still did them.
The judge found that although the evidence was "essential to the proof of serious crimes", he had "no hesitation" in excluding it.
"The search pursuant to the invalid warrant was the last step in an unbroken series of unlawful and unreasonable acts by the police," Justice Hansen wrote in his 2006 judgment.
"There were serious, deliberate and repeated breaches of S21 [of the Bill of Rights Act]. They were unnecessary. "Other lawful investigative techniques were available to the police.
"The officers concerned took a series of shortcuts for no good reason. Their explanations owed much to hindsight and expediency and nothing to necessity."
Mr Carpinter would not comment.
Superintendent Win van der Velde, Waikato's district commander, said police were unable to comment fully as an off-site investigation file on the case was still being retrieved.
No investigation had commenced into Justice Hansen's criticisms.
According to the final judgment, police had detained the Huntly suspect after he had an altercation with his neighbours, and Mr Carpinter and another officer searched his property without a warrant.
Mr Carpinter claimed he carried out the searches because he feared for the safety of a woman he was told might be at the property. Another officer carried out a visual search of the property on Mr Carpinter's instructions.
No occupants were found, but the officer noted a knife, baseball bat, computer scanners and a power cord running to the padlocked backyard shed.
Mr Carpinter then carried out another search of the property with the officer and the two forced entry into the shed, where the drug manufacturing equipment was found.
But Justice Hansen found "force in the submission" by the defence that Mr Carpinter's concern for the woman was an attempt to excuse searches he knew to be unlawful.
Mr Carpinter's notebook and jobsheet showed he was told about the woman more than one hour before the property was searched.
His claim to have recorded the wrong time was dismissed by the judge, who noted that the other officer's records showed it was still 35 minutes after Mr Carpinter's return to the scene that the house was searched.