The Roman empire was at one point ruled by a republic, which is when people vote for people to represent them. which is how most western governments run theses days. the Romans also didnt want any one man to have more power, so people had a certain limit to which they could be in power, maybe for a certain amount of time or having other parts of the government check each other. the top tier position, being consol, meant you could only do that job for a year (i think) and have another person who checks after you. So western goverment took checks and balances as well as the goverments structure. with the power to veto also important.
(hope that helps)