Mamoudou Gassama, the migrant nicknamed "Spiderman" after footage of his daring rescue went viral in May, has since been rewarded with French citizenship and a job in the fire service.
But the four-year-old's father, who has not been named, faces a potential criminal conviction for leaving the child unattended in their 6th-floor apartment, popping out to buy groceries.
Paris prosecutor Francois Molins said at the time of the incident that the father also delayed his return because he wanted to play the popular Pokemon Go game on his phone.
The man's lawyer Romain Ruiz said prosecutors had taken "particularly reductive" elements of the story out of context, but added that the 37-year-old father admitted he had "done something really stupid".
"He is leaving his fate up to the court," Ruiz said.
He added that the father had left home "for between 30 minutes and an hour" and had taken "precautions" to keep the child safe in his absence.
The little boy clambered onto the balcony and appears to have fallen, before miraculously managing to grab the rail of a balcony lower down.
Footage of the incident, filmed by a bystander below, shows him hanging over the edge, a neighbour on the adjoining balcony desperately trying to hold onto him.
Gassama, 22, then scales the building Spiderman-style and pulls him to safety.
In theory, parental negligence carries a maximum penalty of two years in prison under France's penal code, and a fine of up to 30,000 euros ($35,300).
But such a sentence is thought unlikely in the case of this father, who has been allowed to keep custody of his son.
The boy's mother was away at the time of the May 26 incident on a trip to France's Reunion island in the Indian Ocean.
Both parents were said at the time to be extremely shaken by the incident but hugely grateful to Gassama...