A major reason that Congress took over Reconstruction from the president was that the president was moving too slowly
was being too punitive
would not admit the Southern states back into the Union.
would not issue severe enough punishment on the South.

Assemblies do not have written codes of laws. laws are matters for magistrates and courts, not assemblies. codes of law are things such as civil law, criminal law, and constitutional law. what assemblies have are procedures regarding debating, voting and other business they might carry out.  also note that rome had three assemblies: the assembly of the soldiers, the assembly of the tribes, and the plebeian councils.