Italy's highest court on Thursday began reviewing the case of Francesco Schettino, the captain of the Costa Concordia cruise ship that sank in 2012 leaving 32 people dead.
Schettino, dubbed "Captain Coward" by the press for abandoning the stricken vessel during the nighttime disaster, was handed a 16-year and one month jail term in 2015 in a ruling that was upheld last year by an appeals court.
The Court of Cassation in Rome could uphold the verdict or order the case to be reviewed by a fresh appeals court.
It is not expected to rule before early May, lawyers told AFP.
Schettino, 56, was convicted of multiple manslaughter, causing a maritime accident and abandoning ship before all passengers and crew had been evacuated.
He was not in court on Thursday.
Prosecutors have argued his recklessness was to blame for the fate of the giant ship, which struck underwater rocks off the Tuscan island of Giglio on the night of January 14, 2012, and toppled over.
The violation of the ancient code of the sea which states a captain must be the last man off a sinking ship only accounted for one year of the sentence handed down by a three-judge panel in the Tuscan town of Grosseto.
During the first 19-month trial, Schettino was accused of showing off when he steered the ship too close to the island while entertaining a female friend.
The ship had been carrying 4,229 people, including 3,200 tourists.
Schettino's lawyers had insisted the accident and its deadly consequences were primarily due to organisational failings for which the ship's owner, Costa Crociere, its Indonesian helmsman and the Italian coastguard should have shared the blame.
They also argued that it was not the collision, but rather the chaos that ensued due to the ship losing power that was the direct cause of the deaths. Schettino could not be blamed for the mechanical failures, they said.
Costa Crociere avoided potential criminal charges by accepting partial responsibility and agreeing to pay a one million euro ($1.2 million) fine.
Five of its employees received non-custodial sentences after concluding plea bargains early in the investigation.