Judge Taryn Bayley imposed 12 months' supervision and disqualified Mackay from driving for six months.
Unable to produce any documentation or give a reason why she was eligible to come to Northland, Mackay was told by police at a checkpoint on State Highway 1 near Wellsford, to return to Auckland.
Instead, Mackay drove on, reaching speeds of about 140km/h in an unlit 100km zone.
She was followed by a police car, its lights and sirens activated, for about 200m. But she kept speeding up and pulling away, causing police to abandon the pursuit as it became too dangerous.
Another Northland police patrol spotted Mackay near the intersection of SH1 and SH12 and followed her as she travelled at 120km/h. Road spikes were deployed but Mackay drove through them speeding on the rims of her wheels north towards Otaika.
At one point she drove on the wrong side of the road, damaging an oncoming car, which was forced to take evasive action. Judge Bayley accepted counsel Sumudu Thode's submissions a sentence of supervision was the most appropriate, least restrictive outcome.
Thode said Mackay had discovered her sister – a victim of domestic abuse – had been missing for three weeks. Mackay was so worried all rationality went out the window and she simply got in her car and drove. She tried unsuccessfully to explain that to police at the checkpoint.
Mackay was remanded in custody for a week afterwards and also spent time on restrictive bail, Thode said.
The judge acknowledged Mackay has significant mental health issues brought about by "a difficult background marked by mistreatment and violence from others", but that she was now taking steps to address it.
Mackay also had past addiction issues evidenced by her previous convictions, the judge said.
She also acknowledged Mackay's explanation for her offending and concern about her sister, but said, "There is a reason these checkpoints and orders were put in place and that was to keep everyone safe – including you – and it's important the court recognises the seriousness of these types of breaches".
The sentence imposed was designed to assist Mackay and oversee the good work she was already doing to address whatever led to her poor decision making and risk-taking at the time of the incident, Judge Bayley said.
