Showing little emotion, Mr Kerviel hit back at SocGen over the 2010 conviction that held him responsible for massive, risky bets uncovered in 2008.
The 35-year-old claims his superiors knew what he was doing. SocGen denies any part in the trades.
“I am not responsible for this loss ... I always behaved according to rules set by my superiors,” Mr Kerviel said in court in Paris.
At stake for SocGen is whether magistrates will once again exonerate the bank of any responsibility for Mr Kerviel’s massive trading positions, which dealt a big blow to its reputation and forced it to raise capital.
Mr Kerviel portrayed SocGen as having imposed little oversight on its traders, saying he was never told what his official remit was and that his desk regularly flouted its €125m limit.
“My mandate was to make money for the bank,” he told the court.
SocGen’s representative in court, however, said his roles in market-making and arbitrage were clearly defined and that individual traders were responsible for staying within their limits.
Armed with new counsel David Koubbi has already gone on the offensive, filing two lawsuits accusing SocGen of obtaining a verdict under false pretences and of tampering with evidence.
The fresh allegations seek to shift the focus back on to the bank by accusing it of concealing information — such as its tax write-off on Kerviel-related losses — and of responsibility for alleged “blanks” on tapes used as evidence.
The reappearance of Mr Kerviel is the latest reminder of the potential costs to banks of risky trading, coming after JPMorgan recently announced a $2bn (€1.6bn) trading loss. Such events have encouraged regulators to cast a sharp eye on bank practices.
The other shadow looming over the sector is political. With France’s new government threatening to separate banks’ risky activities from their retail operations, French banks have been insisting they do not do overly risky proprietary trading.
Mr Kerviel’s appeal may end up strengthening the view that regardless of whether trades are for clients or for the banks themselves, there needs to be tougher regulation, said analyst Christophe Nijdam.
“This case offers more grist for the new president’s mill,” he said. “If it’s not possible to protect a bank from this kind of trading fraud, it becomes even more urgent to separate this activity from retail banking.”