Roman emperors Arcadius and Honorius issue a new law reenforcing the validity of all previous laws granting privileges to Christian clergy.
According to this new Roman edict:
"We direct that whatever statutes were enacted by Our Fathers at different times with respect to the sacrosanct churches shall remain inviolate and unimpaired.
None of their privileges, therefore, shall be altered and protection shall be granted to all those persons who serve the churches, for We desire that reverence shall be increased in Our time rather than that any of the privileges which were formerly granted should be altered." [CTh 16.2.29]
It's not clear whether the previous laws weren't being followed properly or what might have been the reason why they felt that those laws needed to be formally repeated.