The date of the law is corrupted because in the third consulship of Constantine and Licinius in 313, Licinius was Augustus and not Caesar (another option is 319, the fifth consulship of Constantine and Valerius Licinianus Licinius Caesar in 319, the emperor Licinius's son).
The addressee titled here "gravitas vestra" is unknown. It has been noticed that in the letter cited by Eusebius of Caesarea in his Historia ecclesiastica X.7.1-2. Constantine addresses Anullinus, proconsul of Africa in 313 regarding the restoration of property to the Christian church. The heretics mentioned in the law are the Donatists. See Delmaire, Richard 2005: 122.