Conventional wisdom is that separation-of-power political systems are inherently conservative in the sense of being a status-quo preserving institution. As one adds veto points to the legislative process, the thought goes, less legislation will be implemented relative to a system with fewer veto points.

The argument is seemingly straight forward: Let’s say we have a unicameral legislature in a system of legislative supremacy (a parliamentary system, for example). Let’s say that the legislature enacts N statutes. Now let’s add a veto player. A second legislative chamber. A judicial veto. An executive veto. The veto player will kick out some of the bills enacted by the original legislative chamber. Let’s say the number of bills kicked out by the addition of the veto player is n ≥ 0. So in a separation-of-power system, the thought goes, the number of laws implemented will be (weakly) fewer than the number of laws implemented in a system of legislative supremacy, since N – n ≤ N.

Progressives, particularly in the first half of the 20^th Century, supported unicameralism and opposed judicial review because of their ostensibly status-quo preserving character. (Sen. George Norris, leading advocate of unicameralism during the Progressive Era, complained that bicameralism provided too much check and balance on legislation. He had similar complaints about judicial review at the time – a period of robust judicial application of the doctrine of substantive due process.)

The theoretical claim about the impact of adding institutional veto players on legislative production, while seemingly simple and obvious, is mistaken.

We’ll start with bicameralism, although here I’m cheating somewhat from the start. To wit, in the “strong” bicameralism that exists in the U.S., second chambers can initiate their own legislation as well as kill legislation from the other chamber. (Money bills are an exception in the U.S. Congress, where only the House may constitutionally initiate money bills, as is the case in a number of state legislatures.) So strictly speaking I’m not discussing a pure veto player here. (I plan to consider purer cases in a subsequent post, however.) Nonetheless, the case of bicameralism is notable enough to merit its own attention, despite being proposal-players as well as veto players.

Whether legislative production by a bicameral legislature is less than production by a unicameral legislature depends as a theoretical matter on more than whether a second chamber exists. The overall production of enacted laws – laws enacted by both chambers (we’re ignoring other veto players for now, like executives with a veto) – depends on the amount of legislation originating in both chambers, and the interchamber passage rate: the rate at which legislation originating in one chamber is also approved or rejected by the other chamber. It takes only a little reflection to see that whether this number is greater or less than the amount of legislation implemented in a unicameral system is indeterminate. Theoretically, the bicameral legislature could just as easily generate more legislation relative to a unicameral system as it could generate less legislation.

As I showed some years back in Legislative Studies Quarterly, some states have inter-chamber adoption rates high enough to make it plausible to think (subject to several assumptions that I won’t rehearse here) that some bicameral systems generate more implemented legislation than would be generated by a single body of legislators in that state.

I also looked at legislation before and after cameral transitions in the four U.S. states that have experienced them: Georgia, which moved from a unicameral legislature to a bicameral legislatures in the 1780s; Pennsylvania, which moved from unicameral to bicameral in the 1790s; Vermont which transitioned from unicameral to bicameral in the 1830s; and Nebraska, which transitioned from bicameral to unicameral in the 1930s.

Given the low number of transcameral legislatures among U.S. states, the data are merely illustrative at their very best. Nonetheless, three of the legislatures (Georgia, Pennsylvania, and Vermont) on averaged produced more legislation as bicameral legislatures than they produced as unicameral legislatures. (The increase in legislation for bicameral Georgia, however, was not statistically significant, not that we would want to grant the data from Vermont and Pennsylvania much more merit even though they were.) The unicameral legislature in Nebraska produced more legislation on average than its bicameral legislature.

Again, one does not want to put too much weight on the evidence, given the few cases and the highly contextualized historical conditions faced by the different legislatures over a period of 150 years. Nonetheless, the evidence, such as it is, is consistent with the theoretical claim that that cameral choice should have no systematic effect on legislative production.

As I mentioned above, however, discussing the case of strong bicameralism is a bit of legerdemain in a discussion of the impact of “veto players” on legislative production. I discuss it first only because conventional wisdom often talks of second chambers in bicameral systems as if they were veto players. I should also add that there is a different sense in which, at the micro-level, bicameralism can be understood as a status-quo preserving institution. I expect to talk about that argument, and, more significantly, to consider the impact of purer forms of institutional veto players on legislative production, in future posts.