No reason has been given for the shutdown, which restricts use of social media and messaging applications on mobile phones.
The legal practitioners want the country’s main mobile service operators, Airtel and Tigo, to restore access to platforms including WhatsApp, Messenger, Facebook, Viber and Twitter.
The ban was imposed after a controversial national conference which recommended changes to the constitution which would allow President Idriss Deby to remain in power until 2033.
Deby has ruled the landlocked central African country since 1990.
Access to social media was also suspended in Chad for nearly six months around the April 2016 presidential election. The government said the outage was due to technical problems.
BBC news agency reports Maitre Frédéric Daïnonet, leader of the lawyers that filed the complaint on Saturday, to say the ongoing blackout violates consumers’ rights.
A court in N’Djamena is expected to begin hearing on the matter on 28 August.
Some users in Chad have been able to access social media networks via VPN, though that has meant doubling, even tripling, what they spend for their daily internet connection.