When spoken to by police, Urlich showed signs of being under the influence of drugs, the court heard.
At Tauranga Police Station, Urlich underwent compulsory impairment test procedures and did not complete them to an officer's satisfaction. An evidential blood test revealed he had cannabis in his system.
Urlich's lawyer, Tudor Clee, told Community Magistrate Sherida Cooper that his client's admission to a St John Ambulance officer of his alleged cannabis consumption had been used against him by police.
"It's inconceivable and unbelievable that this ambulance officer thought it was okay to act in some kind of deputised way for police to investigate an alleged crime," he said.
"Ambulance officers are supposed to be there to save lives not to nark on this young man or anyone else for that matter."
Mr Clee questioned the admissibility of the ambulance officer's alleged statement to the attending police officer and circumstances of Urlich's guilty plea.
Urlich claimed he had been pressured into pleading guilty.
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Mr Clee said despite the ambulance officer's diagnosis that there were no signs of concussion, a doctor found the next day that Urlich was suffering from a post-traumatic brain injury.
This was likely to have impacted on Urlich's ability to fully understand his rights which included the right not to incriminate himself, he said.
Urlich lodged a complaint with the Health and Disability Commissioner alleging a breach of the Privacy Act by the ambulance officer, the court heard.
Mr Clee said the defence was yet to receive the findings despite police claiming the commissioner had ruled in the prosecution's favour.
Police prosecutor David Pawson argued that Urlich's application was "meritless".
The Privacy Act allowed emergency services staff to reveal information to police if there was a risk to public safety, he said
"Any first responder — whether it was a St John Ambulance Officer, Fire Service officer or rescue chopper pilot — would be derelict in their duty if they failed to say nothing," he said.
Mr Pawson said there was no evidence Urlich was pressured into pleading guilty.
Mrs Cooper, who rejected Urlich's application, said she was satisfied the St John Ambulance officer had "every right to inform police" about what he had disclosed.
Police clearly needed to know about drug use to ascertain possible threats to safety she said.
Mr Clee said he would seek a discharge without conviction for his client when he was sentenced on March 17.
