The young foreign driver accused of causing a double fatality in Northland has denied being on the wrong side of the road and will be allowed to leave New Zealand before a trial to decide his guilt.

It emerged in court today that United States citizen Reiss Martin Berger, 21, had been in New Zealand on his first visit only hours before the crash about 11pm on Monday.

He had flown in from Melbourne, where he is studying, to spend an extended Easter break with his partner Dita Cavdarbasha, also from the US but wacurrently studying in Auckland.

The couple rented a car and set out for Matauri Bay in the Far North.

But about three hours north, police allege Berger had a "momentary lapse" and the car he was driving crossed the centre line on State Highway 10 and hit another vehicle head on.

The impact killed those in the front seat - James Hamiora and Yvarn Tepania - and injured two others travelling in the rear of the vehicle.

Berger is charged with careless driving causing the two deaths, and three charges of causing injury - including to Cavdarbasha.

Berger's lawyer Mike Dodds said the accident was a "tragedy" for all involved in the accident - not only those killed but his client who was "a young man of good character from a good family".

Berger denied being on the wrong side of the road and had insisted it was those in the other car that had crossed the centre line.

"Mr Berger and his partner are adamant they were on the left-hand side of the road."

The police investigation was still in its early stages and the summary of facts before the court was - at this stage - in draft form.

While bail was a certainty because of the type of charges, there was argument over police should return Berger's passport to allow him to return to Melbourne for university.

Police were opposed to Berger being able to travel, citing previous situations in which foreign drivers involved in serious crashes had left the country and not returned for court hearings.

Dodds said: "This is not someone who is going to disappear. He has nowhere to disappear to. He will be here every time he is obliged to be here.

"He is treating this incredibly seriously and so if his family."

He pointed out to Judge John McDonald that Berger's father, Eric, was in court to support his son. Berger's partner, Cavdarbasha, was also present with one arm in a fresh cast.

The court had also received an affidavit from Eric Berger, an attorney from New Jersey, who offered assurances his son would attend and that a plane ticket could be bought that day to show willingness.

Eric Berger had also assured the court that either he, or Berger's mother Marci, would be in court for every hearing.

Dodds said: "(Berger) takes this extremely seriously. He is obviously traumatised by what has happened. He's going to face up to this. There is no running away from this."

Judge McDonald said jail was "highly unlikely" given the charges faced but they were serious enough to form the basis of an extradition request to the United States if Berger did not return.

He said Berger could retain his passport and return to Australia to continue his studies until the next hearing.

"If you do not return, you will be subject to extradition."