Senior advocate Raju Ramachandran, who has been appointed as amicus curiae by the apex court to defend Kasab, told a bench headed by Justice Aftab Alam that he was not a part of the larger conspiracy for waging war against the nation.
Stressing on Kasab's age as an important factor to commute his sentence, he pleaded for a lenient approach as he was drawn into this by exploitation of religious faith and false ideology.
"The choice before the Supreme Court is life (imprisonment) and irreversible death penalty. It would not be prudent to affirm the extreme penalty," he said.
"Even if I am guilty under section 302 (punishment for murder) of the IPC and other provisions, it cannot be said that I was a part of the larger conspiracy of waging war," he submitted on behalf of Kasab.
Maintaining that the prosecution has failed to prove the case against him beyond doubts, he told the bench that his right against self-incrimination as well as his right to get himself adequately represented by a counsel to defend himself in the case have been violated during the trial.
The apex court had on October 10 last year stayed the death sentence of 24-year-old Kasab, the lone surviving terrorist involved in the November, 2008, Mumbai attack.
In the special leave petition filed by Kasab challenging the Bombay high court judgement, he claimed he was brainwashed like a "robot" into committing the heinous crime in the name of "God" and that he does not deserve capital punishment owing to his young age.