Dunedin barrister Marie Taylor-Cyphers hates drink-driving, and wants the police to do everything in their power to stop it.
People understand police have the authority to breath-test after a random stop on the road, but that understanding becomes murkier if they show up at your house, she says.
"If someone's driving and they're drunk, and you're stopping them while they're driving, that's indisputable."
But when police go to someone's home and say they want to breath-test them, uncertainty enters the equation.
Has that person been drinking and driving, or they have been driving and then started - or continued - drinking at home?
• At a glance
A police officer . . .
- Can enter private property and breath-test someone if there has been a pursuit.
- Can enter private property and breath-test someone if they have "good cause" i.e. reckless or dangerous driving, or driving under the influence of drink or a drug.
- Cannot enter private property for the purpose of a random breath test.
"If the police would just focus on the driving, I would never bother defending it," Ms Taylor-Cyphers says.
"Drink-driving is dreadful - we're killing far too many people, every year.
"But you must be certain you are prosecuting drink-driving, and not prosecuting drinking at home.
"It goes to some of our fundamental human rights - the right to freedom of movement, the right to privacy."
These rights were examined in the Queenstown District Court last month when Judge John Brandts-Giesen threw out charges against an Arrowtown man.
He decided two police officers did not have the right to stay on the man's property once he questioned their authority.
In June last year, the officers spoke to the man on his driveway, having seen him driving moments earlier.
He had pulled into his driveway just after the patrol car activated its red and blue lights and did a U-turn.
There had been no driving fault, but the officer who spoke to him on his driveway thought he appeared unsteady on his feet and smelled of alcohol.
After refusing to undergo a breath screening test and refusing to accompany them, he was arrested and taken to the Queenstown police station, where he again refused a breath screening test, and would not allow a blood specimen to be taken. He was charged with refusing to accompany a police officer and refusing to permit a blood specimen.
Judge Brandts-Giesen said an officer could enter a private property to speak to and breath-test someone who had been driving a vehicle, provided there had been a "fresh pursuit".
The same section of the Land Transport Act referring to "fresh pursuit" also states a police officer needs "good cause" to suspect a person was driving recklessly or dangerously, or driving under the influence of drink or a drug.
Judge Brandts-Giesen found there had been neither a fresh pursuit nor just cause.
"They had seen the defendant and instantaneously decided to follow [the defendant] on what I would describe as a hunch," he said.
Once the officers pulled up on the man's driveway, they were on his property with "implied licence". That is the right of a policeman - or anyone else - to walk on to private property to knock on the front door.
That right was immediately extinguished by the defendant's querying of their authority, he said.
The man's lawyer, Southland barrister Allan Tobeck, said Judge Brandts-Giesen found the legal issues of the case similar to an oft-cited Court of Appeal decision from 1987, Howden v Ministry of Transport.
That case, which remained "good law" after more than 30 years, established police had no implied licence to go on private property to conduct a random breath test, Mr Tobeck said.
Arguments over implied licence usually revolved on whether or not it had been revoked.
"What you have is a situation where the police go to someone's place, using implied licence, and the person is quite hostile, and it's not uncommon for the person who's hostile to say to the police "f*** off", and point towards the road."
He believed many police officers did not fully understand the principle of implied licence.
In last month's case, he believed the officers had acted in good faith and had exceeded their authority inadvertently.
For most people, it was human nature to assume if someone was wearing a uniform, or appeared to have authority, "they must know what they are doing, so I'll do what they say", he said.
Ms Taylor-Cyphers said in almost every case of this type she had handled, the police "genuinely don't understand that what they've done is unlawful".
She had read police policy for breath testing, and found it "a bit vague and ambiguous".
That did not give officers clarity about the extent of their legal authority in such situations.
For example, nowhere did it say officers could not go into someone's home and breath-test them unless consent was given.
"I genuinely think our police, if they were educated around this, wouldn't be doing it.
"They think it's all right because they've been getting away with it for so long."
Implied licence ends at the front door - an officer cannot carry out a breath test in your home unless you invite them in and give your consent.
For most people, saying "no" to the police in that situation takes "pretty big stones", Ms Taylor-Cyphers says.
"Even now, as a barrister, I would have to take a really deep breath before I said to the police `no, you're going to have to leave and I'm calling a lawyer'.
"My advice is to tell them you will make an appointment to go and see them, and that you can't talk right now.
"You go inside and you call a lawyer pretty quick smart, in case it gets more serious."
If police came to your home after receiving a tip-off you had driven home drunk some time earlier, their legal authority rested on how much time had elapsed since you got home.
If it was within 10 minutes, they probably had the right to breath-test you.
The longer the time elapsed, the greater the uncertainty about how much you had drunk before driving and how much you might have drunk since getting home.
• The Otago Daily Times has received no response from the police to a request for an interview to discuss the issues in this story.
