Many countries have bicameral legislatures with two houses, like the United States, United Kingdom, Germany, Russia, etc. Many others are unicameral with just the one, like Norway, Greece, Israel, China, etc. And a few odd examples were tricameral with three. But is there any research into evidenced differences between the two (or more) options? In terms of costs, efficiency, meaningfulness of debate, stability, etc?

Is the variation between national practices sufficiently diverse to rule out meaningful comparisons between unicameral and bicameral, etc, systems? Or can generalities be discussed which would lead to demonstrable arguments for or against one or the other?

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    It's not at a national level, but State Governments in Australia have that variation and might be a valid source to compare. In particular Queensland (with one house) and New South Wales (with both an Upper and Lower house).
    – user7754
    Jul 18 '16 at 5:59

There are numerous studies that look at bicameralism in public choice economics. One general conclusion is that more houses make legislation more difficult to pass, requiring a super-majority of support for legislative change. This can make Tyranny of the majority more difficult, but also lets less legislation pass in general. However, just having two houses isn't sufficient. To this end, economists would consider houses whose "chambers’ demographic characteristics [are] more diverse" more bicameral, more different and requiring a stronger super-majority to enact change.

Buchanan and Tullock, in an early look at bicameralism are concerned with the ability of a Democracy to impose external costs on citizens. They're also worried about decision making costs, the ease of making collective decisions. For example, if everyone had to agree 100% on every issue, making any decision would be impossible, but there can be no external costs imposed on unwilling citizens, on the other extreme, with a simple majority, it's fairly easy to make decisions, but those decisions can impose costs on others (Tyranny of the majority). Buchanan and Tullock find that "if the basis of representation is made sufficiently different in the two houses the institutions of the bicameral legislature may prove to be an effective means of securing a substantial reduction in the external costs of collective action without incurring as much added decision-making costs as a more inclusive rule would involve in a single house." Thus a bicameral legislature may be able help to block legislatures from imposing external costs on citizens, but it would be less of a barrier to decision making than requiring a high % of the legislature to agree before a proposal becomes law.

Another interesting study from the public choice literature is summarized below

Bradbury and Crain (2001) examine the discrete difference between bicameral and unicameral systems in different countries. Specifically, this study examines the effect of the bicameral institution on redistributive spending due to the "Law of 1/n," which is pork-barrel spending fueled by an increase in elected representatives. The study finds that countries with bicameral legislatures experience less 1/n spending than unicameral countries, which is consistent with the hypothesis that adding a second legislative chamber limits redistributive spending

One literature review can be found at The Encyclopedia of Public Choice, page 39, quoted from above. Also see the literature review from Constitutional Political Economy in a Public Choice Perspective section 8.5.


A bicameral legislature would tend to be more expensive to maintain and less efficient in getting things done, but cause fewer issues in terms of concentration of power (and maybe in corruption that often goes along with that).

There have been several academic papers published on the topic; perhaps one or more of those focus on the details you're interested in?

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    Could you point to any specific academic paper which backs your claims? The link you posted is just to a generic google scholar search for "unicameral bicameral"
    – Philipp
    Jul 14 '16 at 20:48
  • No, it's a Google Scholar search showing lots of academic papers, an answer with specificity to match the question.
    – Burned
    Jul 14 '16 at 20:56
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    I was hoping for someone who was familiar with any relevant research to discuss it with a little more expertise than just a link to google. What you've stated as fact are simply intuitions I too had which I had no evidence to substantiate, and so wanted someone familiar with the subject matter to summarise or discuss. I would have thought it goes without saying that an answer ideally should be from someone who is familiar with or can summarise evidenced subject matter. Jul 15 '16 at 9:39

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