A man involved in the drugging and gang rape of a teenage girl was sentenced to preventive detention in the High Court at Christchurch yesterday.

Justice Lester Chisholm gave Gary Maui Isherwood, 26, a minimum non-parole term of 10 years.

"The gravity of the offence is at the highest end of the spectrum," the judge said.

"Sweet," Isherwood responded.

His co-offender, Andrew Clive Hartley, 30, was jailed for 11 years, with a minimum non-parole term of 5 1/2 years.

Both had been found guilty of two counts of administering a class B drug, kidnapping, four counts of sexual violation by unlawful sexual connection and three of rape.

Isherwood reoffended only three weeks after his release from an eight-year sentence imposed in 1999 for getting a 14-year-old schoolgirl hooked on drugs so he could run her as a prostitute.

In this case, the 18-year-old victim, a model, found herself in a motel with Hartley and Isherwood after a night out drinking. She gave evidence that she made it clear she did not want sex, and had simply expected to "chill out".

Instead, she found herself forcibly injected - ritalin and methadone were discovered in her blood - then raped and forced to perform degrading sex acts.

Justice Chisholm said aggravating the offending was the use of drugs to subdue the victim, which the pair administered themselves, her unlawful detention and repeated sexual violation.

"This 18-year-old victim was clearly vulnerable, and you knew it," he said.

It was multiple offending, with the victim's resistance destroyed by drugs.

"There was an element of brutality. Clearly, both of you were only interested in self-gratification."

Evidence showed the pair acted together, with an apparent plan starting early in the evening.

Injuries to the complainant suggested both had been rough, even barbaric. A doctor had been unable to carry out a full examination because of a painful fissure.

Afterwards, the teenager was threatened she would be hurt if she spoke out.

"The complainant is to be congratulated for the fact she came forward and brought you to justice," he said.

Victim impact reports showed she still had a long way to go before she recovered.

Defence lawyer Stan Barker argued Isherwood was not a lost cause, and rehabilitative programmes were an option. He could only ask for a finite jail term, and there could be a legal obstacle to preventive detention.

For Hartley, lawyer Richard Peters said he was in a different category to Isherwood. While he had previous convictions, they were for dishonesty and drug offending.

Crown prosecutor Pip Currie said it was sinister that Isherwood made it clear to the victim he wanted her to work in the sex industry.

But for the fact that she had been able to complain to police, her fate could have been similar to that of Isherwood's 1999 victim.