Valentin Ribet, a 26-year-old lawyer, was among the 90 people massacred at the Bataclan concert hall in the jihadist attacks of November 13.
His parents believe that "serious dysfunctions arose in the Belgian protection and surveillance system that facilitated the terrorists' infiltration into French territory and the commission of these crimes," the Ribets' lawyer Samia Maktouf said in a statement.
The Bataclan dead were among 130 people who were killed at several locations in the French capital that night.
It was also home to Salah Abdeslam, the Paris attacks suspect who is still on the run and who some think may have found refuge in Molenbeek for a time after the killings.
Maktouf said the assailants were "radicalised, trained in jihad and prepared for armed acts in France" in Molenbeek.
Abaaoud and Abdeslam had been able to go back and forth between the two countries before the attacks "despite surveillance by the Belgian authorities," said Maktouf, who represents several victims' families.
In normal circumstances, the court that enforces the convention is a last recourse after other avenues are exhausted.
