In general, upper chambers tend to be the smaller legislative body whose members serve longer terms than their lower chamber counterparts. In bicameral systems, the authority of the two chambers varies widely from country to country. In most cases, the upper chamber has more limited authority than the lower chamber. On the other hand, there are also bicameral systems, like that of the United States, in which the two chambers have equal or offsetting powers and both chambers have equal power to review, amend and adopt legislation. A study conducted of 66 unitary states showed that 54 had unicameral legislatures and only 12 had bicameral systems.
Unicameral legislatures comprise a single, popularly-elected chamber.
Cameral Change Among the newly emerging democratic states, several have replaced unicameral legislatures with bicameral ones. Romanian legislators reported that they favored bicameralism because they felt that it would prevent the concentration of power in the executive branch and would improve the quality of legislation. Romanian critics of this arrangement argue that the chambers are redundant because they have the same authority and the same electoral base. Those critics also note that deadlock between the two houses has undermined the legislature's ability to act as a check on the executive and has diminished the institution's public credibility. Kurgyzstan has also adopted a bicameral system in the post-communist era and, perhaps in part due to vagueness in the constitutional text itself, and legislators are still addressing the problem of resolving differences in legislative texts adopted by the two chambers.