Dr Alan Reay, who owned Alan Reay Consultants, was criticised by the families of those killed for allowing his inexperienced structural engineer David Harding "sole responsibility" for designing the Canterbury Television (CTV) building.
On Tuesday, Reay’s lawyer Kristy McDonald, KC, told the committee her client was an 82-year-old man who had been significantly impacted by the "factually incorrect" complaint against him, stating it should be dropped.
McDonald said the standards back in 1986, when the building was designed, didn’t set out clear supervision requirements and were different from the standards today, stating there was "little to no public interest" in disciplining Reay.
McDonald said it wasn’t until 1996 that specific supervision guidelines were added to the Engineering Code of Ethics.
She asked the committee how her client could have been expected to comply with an unwritten rule that was not clearly set out in the requirements.
She said the evidence before the committee was "a contradictory recollection" of engineers explaining what they did at the time in terms of supervision.
McDonald said there was a real risk of "hindsight bias" in this case and the onus was not on Reay to prove his innocence.
Chartered professional engineer Dr Andy Buchanan told the committee the first question an engineer in New Zealand would consider was how the building would resist an earthquake.
He said damage to buildings during an earthquake was "entirely expected" but even in a major earthquake the aim should be for "no loss of life".
Buchanan said it was difficult to assess the question of supervision as different projects required different levels of supervision as well as the type of engineer carrying out the design work.
From his own engineering experience, there was "constant internal discussion" with others, Buchanan said, stating: "Designing a building is not a simple business".
Buchanan said even as a senior engineer in the 1970s he was still supervised and assisted by other senior partners, adding that he also supervised some junior engineers.
Buchanan was not aware of any supervision requirements from IPENZ in the 1980s but "if someone had a difficult decision to make, they would seek advice".
Yesterday committee chairman Andrew McMenamin outlined the complaint against Reay.
In the aftermath of the earthquake, the Canterbury Earthquakes Royal Commission found the structural design of the CTV building was seriously deficient in multiple ways and it was alleged Reay knew his engineer Harding was inexperienced but failed to adequately supervise him.
During day one of the hearing spokesman for the CTV families Dr Maan Alkaisi said their experience of losing loved ones was made even more painful by the lack of accountability by Reay.
Alkaisi said Reay "risked people’s lives", resulting in "one of the worst engineering failures in the country" and since the tragedy, had not taken accountability.
Reay strongly denied the allegations, stating he had good reason to believe Harding was sufficiently competent to undertake the work he did.
In September Reay sought a judicial review of the complaint process by Engineering New Zealand, formerly the Institution of Professional Engineers (IPENZ), in the High Court at Wellington which was dismissed in October by Justice Paul Radich who said there was "genuine public interest" in having the complaint heard.
The complaint against Reay was first raised in December 2012, after the release of a Canterbury Earthquakes Royal Commission report, which found Reay breached the 1986 IPENZ Code of Ethics.
The disciplinary hearing is expected to finish on Wednesday.
Emily Moorhouse, Open Justice reporter