The Crown is seeking forfeiture of nearly $1 million of assets from a man convicted of conspiring to deal in illegal party pills in 2016.

Hugh James Robinson, who was 61 at the time of his appeal against his convictions in 2017, is challenging the Crown's case in detail at a hearing in the High Court at Christchurch.

He is representing himself, with his wife Svetlana, at the hearing before Justice Cameron Mander.

Crown prosecutor Karyn South said the Crown was seeking $952,349 from the Robinsons, several companies and a family trust.

The Crown has filed affidavits putting its case and is calling two witnesses so that they can be cross-examined by Robinson.

Robinson was found guilty at a Christchurch District Court jury trial in 2016, on charges of possession and conspiring to deal in party pills worth $240,000 on the street, and a firearms offence.

When the jury returned its verdicts, trial Judge Alistair Garland asked for Robinson's criminal history, then told the jury he had been convicted in 1992 for cultivating cannabis and importing LSD and imprisoned for seven years and six months.

That was apart from a conviction for possession of BZP – party pills which were declared illegal in 2008 – which the jury was told about during the trial.

Robinson denied conspiring to sell the class C drugs, possession of them at his house, car, business premises, and storage unit, and unlawful possession of a sawn-off shotgun and ammunition at a storage unit in Russley Rd.

He said his son, Jamie Daniel Robinson, 29 - who has served a jail term for drug offending - was responsible for the drugs.

Hugh Robinson said he originally thought the pills were leftover from when his company, High Performance Health, stopped producing them. He said in evidence that a series of cash transactions concerned synthetic cannabis sales while it was still legal, and sale of assets and artworks. The artworks included pictures by Picasso and Salvador Dali which Svetlana Robinson had brought back from Russia.

Robinson was jailed for four years, but appealed his conviction to the Court of Appeal, claiming a miscarriage of justice because of pre-trial rulings by two judges. The Court of Appeal dismissed the appeal.

During his cross-examination at the High Court hearing on Monday, Hugh Robinson accused the police of putting "deliberate mistruths" into their forfeiture affidavits, and said he could not accept that they were "innocent mistakes".

The hearing is continuing.