Judgment on the professional conduct of apartheid-era chemical warfare expert Dr Wouter Basson is due to be delivered on Wednesday.

The six-year long hearing, initiated by the Health Professions Council of SA, was held at the organisation's offices in Pretoria.

Jaap Cilliers SC, for Basson, presented closing arguments in November.

He said Basson should be acquitted as the hearing was unfair and unreasonable, and the HPCSA had not proved its case.

Basson was the project officer of Project Coast, a secret biological and chemical warfare research project which violated international protocols and conventions.

Basson allegedly acted unethically during his involvement in the project from the 1980s to the early 1990s.

Cilliers argued that Basson's conduct at the time was mainly to ensure the safety of the populace in the least harmful way.

A charge sheet was provided in 2006, five years after the complaint was laid, said Cilliers.

Basson is accused of acting unethically by being involved in the large-scale production of Mandrax, cocaine and teargas, of weaponising teargas, and of supplying it to Angola's Unita leader Jonas Savimbi.

He is also accused of acting unethically by providing disorientating substances for cross-border kidnappings and making cyanide capsules available for distribution to operatives for use in committing suicide.

In 2002, Basson was acquitted by the High Court in Pretoria of criminal charges arising from his conduct.

The HPCSA reviewed the judgment to establish if there were grounds to continue with an inquiry.

The State appealed against the decision in the Supreme Court of Appeal, but the appeal was dismissed.

The State then went to the Constitutional Court but it was dismissed in September 2005.