A court in Dubai, in the UAE, has jailed two men for 15 years for the abduction and sexual assault of a 15-year-old French-Swiss boy.
Ms Robert is campaigning for a change in homosexual rape law
The men, one of whom is HIV positive, took the teenager to the desert and raped him at knifepoint.
The victim's mother, Veronique Robert, says the authorities lied about the defendant's medical status to hide the fact that Aids is present in the UAE.
"Fifteen years is nothing for someone who knew he had Aids," she said.
A lawyer for the family said they would appeal against what they saw as a too-lenient sentence. A juvenile court is trying a third suspect in the same case.
The defence had claimed the victim had consented to sex and had lied to the authorities.
Ms Robert has been campaigning to change the law in the United Arab Emirates to recognise homosexual rape as a crime and for more openness about HIV and Aids.
The country - a collection of seven conservative desert sheikhdoms - has in recent years become a booming regional business centre.
Her son testified during the trial, after having initially fled Dubai fearing he would be prosecuted for homosexuality, a crime in the Emirates.
Ms Robert has said during a forensic examination the police doctor accused her son of being homosexual, implying the incident was consensual.
She alleges that initial denials by officials about the 36-year-old's positive HIV test also meant her son missed out on possible treatment.
"Aids is a taboo subject here... The government played with the life of my child," she said after her son testified in November.
The defendants' names and specific convictions cannot be made public because of confidentiality clauses in Dubai's legal system.
Dubai officials have defended their handling of the case, without commenting on the mother's accusations.