Why did the allies adopt a "europe first" strategy?

They adopted a Europe First strategy because only Germany was considered to be a long term threat that needed to be stopped as soon as possible. Japan was not perceived as such a great threat.

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.