Three Branches. Much like the modern U.S. government, most of the government of ancient Rome can be divided into three branches: legislative, executive, and judicial. There are, however, some differences in function, and the Roman government had at least one important component (the Senate) which does not fit this scheme well.

Legislative Branch. The legislative bodies were two popular assemblies with largely overlapping authority. In addition to lawmaking, these assemblies also elected the magistrates and, in a few instances, sat as courts of law. All adult male Roman citizens were eligible to vote in these assemblies, but they had to be present in person (at Rome) to do so. Both assemblies used group voting. That is, the electorate was divided into a number of groups, and the majority in each of these subunits determined its...