Issued in the last days of the rule of Emperor Galerius.
At that point there was a tetrarchy Galerius–Constantine–
Licinius. Roman luminary Maxentius also a party to the edict. The edict grants universal religious toleration and restitution (306–313 CE). However, Constantine will later backtrack (see 312 CE, just below) on the universal aspect of the toleration.
[As regards Galerius, the Edict of Toleration represented an about–face in his posture towards Christianity.]