Guarding the Guardians
Legislative Self-Policing and Electoral Corruption
in Victorian Britain 1
Andrew Eggers†

Arthur Spirling‡

Abstract

We offer an institutional explanation for the dramatic decline in corrupt practices thatcharacterizes British political development in the mass suffrage era. Parliamentary candidates who faced corruption charges were judged by tribunals of sitting MPs until 1868,
when this responsibility was passed to the courts. We draw on theory and empiricalevidence to demonstrate that delegating responsibility over corruption trials to judges
was an important institutional step in cleaning up elections. By focusing on an institutional explanation for Victorian electoral corruption (and its demise), we provide an
account that complements the existing literature while offering clearer implications forcontemporary policy debates.

1

First version: April 1, 2011. This version: April 25, 2014. We thank Jim Alt, Justin Fox, Alexander Hirsch,
Robert van Houweling, Robert Powell, Torun Dewan, Nolan McCarty, Gary Cox and seminar audiences at Yale
University, the University of California at Berkeley, Harvard University, New York University, and the annual meetingsof APSA and EPSA for useful comments. We are very grateful to our excellent research assistants: specifically,
Alexander Fisher and Vicky Jung for research assistance and data collection on election petitions and Lauren Fulton
and Colby Wilkason for data collection for our database of MPs’ speeches, votes, and election results. Financial
assistance from IQSS is gratefully acknowledged.
†
Department of Government, London School of Economics. email: a.c.eggers@lse.ac.uk‡
Department of Government and Institute for Quantitative Social Science, Harvard University.
email:
aspirling@gov.harvard.edu

11Introduction

The magnitude of political change in 19th century Britain has made it one of the most widely
studied episodes of democratization in history (e.g. Bagehot, 1873/2011; Trevelyan, 1922; Gash,
1952; Woodward, 1962; Cox, 1987; Acemoglu and Robinson, 2000). While scholars have paid
much attention to the massive expansion of the suffrage during this period,2 the decline in corrupt
practices in election contests is no less remarkable (O’Leary 1962, Hanham 1978, 262, Kam 2009).
Today, suffrage is essentially universal in all democracies but the corrupt practices that plagued
Victorian elections, such as vote buying, turnout buying, coercion by landlords and employers, evenviolence, persist in many developing countries (Stokes, 2005; Hyde, 2007; Nichter, 2008; Myagkov,
Ordeshook and Shakin, 2009; Gonzalez-Ocantos et al., 2010). It remains relevant, therefore, tounderstand why electoral corruption was so widespread in mid-19th century Britain and why it
subsequently declined.
Several explanations for the prevalence and decline of Victorian electoral corruption have received well-deserved attention. O’Leary (1962) emphasizes permissive campaign finance arrangements and open voting (i.e. the absence of the secret ballot), pointing to the 1872 Ballot Act andthe 1883 Corrupt and Illegal Practices Act as key regulatory measures that eliminated corrupt
practices. Cox (1987) highlights the attractiveness of corrupt electioneering in small electorates,
pointing to franchise extension as the decisive step toward cleaner elections. Stokes et al. (2013)
stresses that vote buying was preferable to programmatic campaigning because voters were poor,
suggesting that industrialization “killed” vote buying in Britain in part by making most voters too
wealthy to bribe.
In this paper, we emphasize an institutional explanation for the prevalence of electoral corruption in 19th-century Britain that arguably has more direct relevance to contemporary contexts:
we focus on the procedure by which electoral corruption statutes were enforced. As we explain in
2

Phillips and Wetherell (1995, 413) report that an estimated 400,000 individuals were eligible to vote prior to the1832 Act, while Craig (1989) has some 6.7 million people eligible to vote in the 1900 General Election.

2

greater detail below, the chief deterrent against vote buying and other corrupt electoral acts was
the threat that, having won the seat, one would be unseated as the result of a successful election
petition filed by the losing candidate. Until 1868, election petitions were handled by small ad hoc
tribunals of MPs who, after reviewing the evidence and legal arguments, issued formal rulings. Our
main claim in this paper is that the unreliability of these tribunals (as illuminated most clearly by
the partisan favoritism we detect in their rulings) contributed substantially to the prevalence ofcorrupt electoral practices in this period. Replacing MPs with judges in 1868, we argue, appears tohave led to more reliable adjudication and thus contributed to the subsequent decline in corruption.
One of the key challenges facing any attempt to explain electoral corruption in Victorian Britain(or indeed any other setting) is that we do not directly observe the corrupt practices we are trying
to explain. In the case of Victorian Britain, historians and political scientists have relied heavily oncommittee reports from election petition trials for evidence of the nature of electoral corruption at
the time (e.g. Seymour, 1915; O’Leary, 1962; Richter, 1971; Kam, 2009). Scholars have also used
the number of petition trials following each election as a measure of the prevalence of corruption
itself; for example, scholars have interpreted the high number of petitions filed in the 1850s and1860s as evidence that electoral corruption was at its worst in mid-century (Porritt, 1906; Rix,
2008; Stokes et al., 2013). In this paper we focus on election petition trials not as a barometer ofelectoral practice but as a determinant of electoral practice. We recognize that the decision to file apetition, like the decision to engage in corrupt electoral tactics, was strategic. The incentives to filea petition alleging vote-buying, like the incentives to engage in vote-buying, depended in part on
the ability of the tribunals deciding petition trials to correctly ascertain guilt and innocence. Our
goals in this paper are to try to understand how these incentives may have varied with institutionalchanges in the process for adjudicating petitions and, in doing so, to shed additional light on thecauses of electoral corruption in Victorian Britain.3
3

Although this is not the focus of our paper, one clear implication of recognizing the strategic nature of filing
petitions is that we must use care in trying to infer the nature or extent of electoral corruption from the set of
petitions that were filed.

3

We accept the consensus view that electoral corruption was much less common by 1900 thanit was in 1850, and we accept that there are multiple causes of this decline whose independent
contributions can never be neatly disentangled.4 Our approach in this paper is to rely on a mix oftheory and empirical evidence to make the case that politicized and arbitrary handling of election
petitions by tribunals of sitting MPs contributed to mid-century electoral corruption and thatreforms that judicialized the process contributed to corruption’s decline. We contend that our
focus on enforcement is justified in part by the enduring policy relevance of the question of how
legislators should be regulated. Other reforms such as the secret ballot and franchise extension
also likely contributed to the decline in corruption in Victorian Britain, but no democracy today
questions whether ballots should be secret or whether poor people should be allowed to vote; bycontrast, democracies continue to differ markedly in how they decide election disputes (Massicotte,
Blais and Yoshinaka, 2004). The constitutional issues at stake in 19th century Britain (i.e., whether
elections should be policed by the legislators who compete in them or by separate entities) remain
alive today.
After providing a brief institutional background of electoral corruption tribunals in Victorian
Britain, we address the question of how the accuracy of the decisions made by these tribunals
would have affected the prevalence of electoral corruption. We study this question by analyzing amodel in which candidates choose electoral tactics (corrupt or non-corrupt) and the winner may
subsequently face a corruption trial. Intuitively, it may seem obvious that error in the outcome ofthese trials – i.e., acquitting an MP who was actually guilty of corruption or convicting one who was
actually innocent – would encourage corruption, because greater error increases the attractivenessof using corrupt tactics and decreases the attractiveness of not using corrupt tactics. The situation
is not so clear when, as was the case in Victorian Britain, MPs are only put on trial when the losing
4

For example, the Second Reform Act (1867), Parliamentary Elections Act (1868), and Ballot Act (1872) all likely
had an impact on electoral corruption; because they were enacted in such rapid succession, it is difficult to measure
the effect of any single reform, let alone disentangle the impact of legislative reform from that of broader socialchanges.

4

candidate strategically chooses to file a (costly) petition, because error could either encourage or
discourage losing candidates from filing. We show formally that error does in fact undermine
deterrence in this setup when the cost of filing a petition is high, a condition we argue was likely
met in our setting.
We then provide a mix of empirical evidence to indicate that the adjudication of electoral
petitions by tribunals of sitting MPs was indeed quite error-prone. Our strongest evidence is drawn
from a newly-collected dataset of rulings issued between 1840 and 1880. A remarkable feature of
trials heard by committees of MPs is that each petition was heard by a different set of MPs, with thepartisan majority alternating from one tribunal to the next; effectively, it was as good as random
whether a given case was assigned to a Liberal or Conservative tribunal. Taking advantage ofthis unique feature of these cases, we show that tribunals of different partisan majorities convicted
defendants at strikingly different rates, suggesting inconsistency and error in judging MPs’ guilt.
The error that we detect in these decisions suggests pervasive partisan favoritism: Liberal tribunals
were especially likely to convict Tory defendants and vice versa. We also show that this partisan
error was sharply lower in the period after 1868, when responsibility for judging election petition
cases was passed to the courts. In conjunction with contemporary accounts questioning the legal
competence of tribunals of MPs as well as data on petition and conviction rates over time, ourempirical evidence points to the 1868 reform as an important contributor to the overall decline incorruption during the period.

2

Adjudicating election petitions in Victorian Britain

Electoral corruption in Victorian Britain was proscribed by common law and over a dozen statutes,
some of which were hundreds of years old.5 These laws were enforced by what amounted to a
5

In an 1850 treatise, Erskine May counted 61 statutes relating to the election of MPs, 16 of which related tobribery, treating, and intimidation; these laws were consolidated in the 1854 Corrupt Practices Prevention Act (May,1850).

5system of private lawsuits among candidates, adjudicated until 1868 by tribunals of sitting MPs in
the House of Commons. In this section we describe the operation of this system in order to place
the subsequent analysis in context.
Historically, the issue of what body had the right to determine who was elected to Parliament
was a matter of serious constitutional importance. The Tudor monarchs had claimed the right tohear electoral corruption charges and other election disputes in their own courts; in the early 17th
century Parliament secured this right for itself as part of a broader assertion of independence fromthe Crown (Porritt, 1897).6 Over the next two centuries the House of Commons employed various
procedures for conducting trials of election petitions.7 Finally in 1839 the House settled on a newprocess by which a General Committee on Elections would be responsible for selecting a committee
of seven members (five after 1848) to hear each petition; by convention (as described in more detailbelow) the majority party on these committees alternated from one case to the next. Considerable
effort was devoted to the design of these tribunals: committees were to be small in order to makeeach member take his work seriously and to not occupy too much of the House’s resources at any
one time; members of the tribunals were selected according a rotating method in order to distributethe burden fairly among MPs while avoiding the possibility of partisan or personal favoritism inassigning MPs to hear particular cases (Warren, 1853).
Despite these efforts to ensure competence and impartiality on election petition tribunals, dissatisfaction with the handling of election petitions periodically surfaced. The criticisms came toa head in 1867 when the Conservatives under the leadership of Disraeli put forward a proposal
to remove jurisdiction over election petitions from the House of Commons and delegate the responsibility to higher court judges. In debate surrounding the measure, MPs offered a variety of
6

The constitutional significance of the legislature’s right to certify its own members in English history is reflectedin the United States Constitution, Article 1, Section 5, Clause 1, which states, “Each House shall be the Judge ofthe elections, Returns, and Qualifications of its own Members. . . ” (Jenkins, 2004; Reed, 1890).
7
Before 1770 petitions were heard either by the Committee on Privileges and Elections or by the whole House;
after 1770, each petition was heard by a different select committee of eleven members chosen by the litigants’ fromthirty-three randomly-selected MPs (The Practice on Election Petitions, 1837).

6

opinions about whether tribunals of MPs were suited to the task of deciding electoral corruption
cases against other MPs. The common thread running through MPs’ complaints about the present
method of hearing cases was that these tribunals issued seemingly arbitrary decisions on the basisof limited insight into either the law or the facts of the cases before them. Reporting on the deliberations of a committee assigned to investigate the matter, Sir Robert Collier (Liberal MP for
Plymouth) stated that “Almost everyone was agreed that the jurisdiction on Election Petitions was
not satisfactorily exercised by the Committees of that House” (HC Debs, May 21 1868, Col 662).
He emphasized three shortcomings widely discussed in the broader debate. First, petition trials
took place at Westminster, rather than in the constituency where the election took place, which
several speakers argued made it more difficult for committees to find out what happened in theelection.8 Second, petition hearings could be held only when Parliament was in session, meaningthat a considerable delay could intervene between the election and the trial, which critics thought
made it even more difficult to arrive at the truth.9 Third, MPs simply were not on the whole qualified “to decide the intricate questions arising in election cases”, such as whether the petitioner ina particular case had convincingly shown that the defendant had authorized corrupt tactics. In thewords of Edward Pleydell-Bouverie, Liberal MP for Kilmarnock, the problem with these tribunals
was that “they were more or less incompetent. They were presided over by Gentlemen who had nolegal training – who were not skilled in the law of evidence, or capable of dealing with questions ofcomplicated law and fact.”10
Although it is beyond the scope of this paper to determine why MPs criticized what they
perceived as incompetent adjudication of electoral corruption trials, it is clear from reading the8

As argued by Sir Charles Selwyn, Conservative MP for Cambridge University and Solicitor General, “When awitness was examined in his own town with the people standing before and around him, who all knew what hehad been doing, it was almost impossible, from the instant murmur or gesture that arose, for the witness to tell an
untruth. The case was often very different when the witness was examined in London . . . .” (HC Deb, 25 June 1868,col 2178)
9For example, in the words of George Ward Hunt, Conservative MP for Northamptonshire North and Chancellorof the Exchequer, it was desirable to have trials as soon as possible after the election “[b]ecause when there wasa considerable lapse of time between the complaint and the investigation there was greater opportunity for having
resort to manoeuvres for getting rid of witnesses and suchlike proceedings.” (HC Debs, May 21 1868, Col 687)
10
HC Debs, July 6, 1868, Col 724.

7

contemporary debate that they generally believed that inaccurate adjudication undermined deterrence. That is, the general understanding was that by making these decisions more accurate they
could discourage electoral corruption, which was thought to be a priority following the expensive
and corrupt elections of 1865 (O’Leary, 1962, pp. 27-31). For example, in advocating a bill tohave judges rather than MPs decide election corruption cases, George Ward Hunt (then Conservative MP for Northamptonshire North and Chancellor of the Exchequer) argued that “the planembodied in the Bill was that which would give the public the greatest amount of confidence inthe decisions on Election Petitions, and that it would effectually tend to check bribery and corruption.”11 Commenting on the same bill, John Stuart Mill (who at this time served as a Liberal MP
for Westminster) argued that reforming the process of election petitions would make it harder for
unfit candidates to buy their seats and thus elevate the quality of MPs on average:

The Bill was a bold attempt to grapple with an acknowledged political and moral evil. . . .
It was no party measure, and no party were interested in passing it, except the partyof honesty. They desired to diminish the number of men in this House, who came in,
not for the purpose of maintaining any political opinions whatever, but solely for the
purpose, by a lavish expenditure, of acquiring the social position which attended a seatin this House, and which, perhaps, was not otherwise to be attained by them.12

Contemporaries thus saw a causal connection between the shortcomings of the election petition
system and the pervasiveness of electoral corruption in Victorian Britain. Our task is to assess
whether they were correct: should we count problematic self-regulation as one of the importantcauses of electoral corruption? We see this task as having both a theoretical and an empiricalcomponent. The theoretical component requires us to determine whether in principle adjudicatory
error undermines deterrence, even in a context where lawsuits are filed strategically.13 The empirical
11

HC Debs, May 21, 1868, Col 688.
HC Debs, May 21, 1868, Col 686.
13
The link between adjudicatory error and deterrence is complicated in general (e.g. Craswell and Calfee, 1986),128

component requires us to determine whether, in fact, MPs were especially poor adjudicators ofcorruption petitions and whether judges were any better. We now address each of these components
in turn.

3

Adjudicatory Error and the Prevalence of Electoral Corruption

Suppose that electoral candidates have access to corrupt tactics such as vote buying or fraud; acandidate who uses these tactics is thereby more likely to win, but he is also more likely to lose
his seat in a post-election corruption trial.14 The purpose of this section is to investigate how
candidates’ incentives to engage in corrupt tactics depends on the accuracy (or, conversely, errorrate) of the decisions handed down at the possible trial stage. First we show that, if the probabilityof a trial is fixed and exogenous, equilibrium corruption is weakly lower when error is lower. Does
this intuition extend to a situation where lawsuits are filed strategically? We show that it does aslong as the cost of filing petitions and/or the starting level of error is sufficiently high.15

3.1

Setup: baseline modelTwo evenly-matched candidates compete for office. At the electioneering stage, each candidate
chooses between running a clean campaign (C) or a dirty one (D). Holding fixed the other player’s
action, playing D increases a candidate’s probability of winning by δ ∈ [0, 1/2]; it also costs d > 0.
Table 1 depicts the probabilities of victory corresponding to different combinations of campaign
actions.
After the winner of the election is determined, a process of enforcing corruption statutes begins.
and especially in a setting in which private parties must decide whether or not to file suit (e.g. Polinsky and Shavell,
1989; Hylton, 1990)).
14
We use male pronouns because all MPs and candidates in this period were men.
15
By contrast, Polinsky and Shavell (1989) analyze a situation in which the plaintiff’s beliefs about the defendant’s
guilt depend on the defendant’s action but are exogenously given. Hylton (1990) derives the plaintiff’s beliefs about
the plaintiff’s guilt as part of the equilibrium under a specific negligence rule.

9Table 1: The electoral game: probabilities of winning as a function of players’ actions
Candidate 2
Clean

Dirty

Clean

1/2, 1/2

1/2 − δ, 1/2 + δ

Dirty

1/2 + δ, 1/2 − δ

1/2, 1/2

Candidate 1

We start by assuming that with a fixed probability p the winner is put on trial. A non-strategic
tribunal correctly judges guilt and innocence with error rate θ ∈ (0, .5): if the winner played C hewill be convicted with probability θ; if he played D he will be convicted with probability 1 − θ.16
The payoff to the winner is 1 if he keeps his seat (either because he was not put on trial or because
he was not convicted) minus d if he played D; the loser gets 0 if he played C and −d if he playedD.

3.2

Analysis: baseline model

The Nash equilibrium of the game consists of a pair of electioneering strategies. Denote by α theprobability that one’s opponent plays D. Then the payoff from playing C is
πC (θ, p, α) =11
α − δ + (1 − α)22× 1 − pθ

(1)and the payoff from playing D isπD (θ, p, α) =




1
1
α + (1 − α) + δ × 1 − p + pθ
2
2

(2)

16
The error rate need not be the same for guilty and innocent defendants, but assuming symmetry makes theanalysis simpler while still conveying the main point.

10where in each case the first term is the probability of winning and the second term is the probabilityof retaining the seat, conditional on winning. Setting α to 0 or 1, we find that a Nash equilibrium
in which both players play C can be sustained only if1

θ< 2

p − δ(1 − p)∗
≡ θCp(1 + δ)(3)

and a Nash equilibrium in which both players play D can be sustained only ifθ>12p − δ

p(1 − δ)

∗
≡ θD
.

(4)

∗ > θ ∗ , which indicates that there is an interval in which both equilibria (andAlgebra reveals that θCDa mixed-strategy Nash equilibrium) can be sustained. We thus have an intuitive result relating error
to deterrence: for a fixed probability of a trial taking place, candidates are deterred from corruption
if the rate of adjudicatory error is low but not if it is high; for intermediate ranges there are multiple
equilibria. If we employ a common refinement requiring that players coordinate on the equilibriumwith the highest payoffs, we have a weakly monotonic positive relationship between adjudicatory
error and corruption.

3.3

Analysis: strategic filing of petitions

Now suppose that, after the election has taken place and a winner has been chosen, the winnerfaces a trial only if the loser chooses to pay a cost k to file a petition and sue the winner. The trial
then takes places as assumed above: a non-strategic court assesses guilt and decides correctly withprobability 1 − θ. If the winner is convicted, the loser receives a benefit b < 1; aside from the costs
and potential benefits of filing suit, the payoffs are the same as above.17 At the point when the17

We assume for simplicity that only the petitioner pays legal costs; in fact, both sides of course sustained legal
costs in the event of a petition trial. See Appendix A.2 for discussion of how the analysis depends on the distributionof costs. Note that each side paid their own costs regardless of the outcome of the lawsuit, in contrast the usual“English Rule”, in which the loser pays all legal costs (Warren, 1853, pp. 650-652). An exception was made for11loser chooses whether to sue, neither player knows the campaign action chosen by his opponent; theloser does however know his own campaign action and can use that information to make inferences
about the winner’s action.
When enforcement depends on the loser’s decision to file suit, the relationship between error
and deterrence is not so intuitively clear: if the probability that the winner played dirty is below
1/2, then greater error could lead to more suits being filed (and thus better deterrence) because anerroneous decision would tend to benefit the petitioner. Indeed, the analysis is substantially more
complex when we make lawsuits strategic. In order to manage the complexity, we begin by making
the following assumptions:2dAssumption 1. δ ≥ 1−b+2k.

Assumption 2. Both candidates play D with certainty if doing so constitutes an equilibrium.
As explained in Appendix A.1, Assumption 1 ensures that there are no asymmetric pure-strategy
Nash equilibria (i.e. equilibria where one candidate plays C with certainty while the other plays
D); Assumption 2 eliminates the complication of multiple pure-strategy Nash equilibria.
Define α∗ (θ) as the candidates’ equilibrium probability of playing D, as a function of θ.18
We focus on sequential equilibrium, which requires that the loser’s belief about the winner’s guilt
reflects the winner’s true probability of playing dirty, updated using Bayes Rule by his own electoral
strategy. The following proposition clarifies the conditions under which reducing error tends toencourage corrupt electioneering:
Proposition 1. Given θ0 < θ: α∗ (θ0 ) ≤ α∗ (θ) if k > b/2 or θ > 1/2+d−δ(1−b+k).
1−δ(1−b)
Proposition 1 essentially says that reducing adjudicatory error weakly reduces corruption if thecost of suing is high enough relative to the benefit of winning the suit, or if the starting level ofadjudicatory error is high enough.
“frivolous and vexatious” suits.
18
Given Assumption 1 and the symmetry of the game, it is reasonable to focus on symmetric equilibria.

12

Proof. First, note that if δ < d candidates play C regardless of other parameter values, and if k > 1
no lawsuits are filed regardless of other parameter values; θ thus has no impact on behavior in thosecases. For δ > d and k < 1, α∗ (θ) is as depicted in Figure 1 (under Assumptions 1 and 2). (Details
in Appendix A.1.) At any point where k > b/2, α∗ is weakly increasing in θ. The relationshipbetween θ and α∗ is non-monotonic where k < b/2, but for θ > 1/2+d−δ(1−b+k)
we have that α∗ = 1
1−δ(1−b)whereas for θ < 1/2+d−δ(1−b+k)
we have that α∗ < 1.
1−δ(1−b)
The idea that making the trial outcome more accurate would deter cheating seems intuitive,
especially in a situation (like the baseline model above) in which the probability of a suit is exogenous. Proposition 1 (and the underlying analysis in Figure 1 and Appendix A.1) shows that thisintuition extends to a situation with strategic petitioning as long as the cost of suing is high enough(or the error rate is high enough). When suing is expensive, losing candidates sue only when it islikely that the winner was corrupt; in that situation, increasing the accuracy of adjudication makes
losing candidates even more likely to sue, amplifying the deterrent effect of accuracy. When suing
is inexpensive, however, the intuitive relationship between accuracy and deterrence breaks down:
losing candidates sue so readily that the marginal defendant (i.e. the defendant who is marginallyworth suing) is probably innocent, such that making trials more accurate makes suing less attractive
and thus fails to deter corruption.

3.4

Costs and benefits of filing petitions in Victorian Britain

The foregoing analysis highlights the importance of petitioning costs in determining the effects ofadjudicatory error in a setting with strategic petitioning. Before providing evidence of substantial
error from tribunal decisions in the next section, we first briefly provide evidence that the costs ofpetitioning were indeed high relative to the benefits and thus that higher adjudicatory error would
have contributed to higher corruption rates.
In debate and in select committee reports MPs regularly complained about the high cost of
13

1/2

Figure 1: Summary of equilibrium corruption rates (α) as a function of adjudicatory error (θ) andthe cost of filing a lawsuit (k)

θ=

(1 2

+d

− δ(

1−

b+

k))

(1 −

δ(1

−b

α* = 1))θ=

0 < α* < 1

1−

θ

k

θ=

b

α* = 0

k
b

∂α*
∂θ

∂α*

<0

∂θ

>0

0

k=b 2

0

1/2

b = 0.85

1kNote: Figure assumes b = .85, d = .05, δ = .25, as well as Assumptions 1 and 2. As explained in text, k is thecost of filing a petition, θ is the probability of adjudicatory error, b is the benefit of winning a petition, and α is theequilibrium probability of playing “dirty” electoral strategies.

14petitioning a sitting MP; indeed, one of the main stated justifications for reforming the system ofhearing petitions in 1868 was to reduce the cost of petitioning and thus encourage trials to take placein constituencies where corrupt practices were widely suspected.19 To take an extreme example,
George Melly, Liberal MP for Stoke-on-Trent, noted in debate in 1868 that a recent petition contest
had cost the petitioner £11,000; another MP gave an example in which the legal costs amounted
to £500 per day for 6 days.20 The benefits accruing to the winner of a petition contest appear tohave been limited in comparison: in the vast majority of cases a successful petition resulted in aby-election being held to fill the seat of the guilty MP, and an analysis of these by-elections showsthat a candidate of the same party as the unseated MP was elected in over two-thirds of thesecases; not only did the petitioner himself rarely claim the seat, then, but the petitioner’s party
usually did not benefit either. As an additional piece of evidence that the costs of petitioning werehigh relative to the benefits, the proportion of constituency contests resulting in a petition hearing
never rose much above 10%; if petitioning were cheap relative to the benefits, we would expect ahigher petitioning rate even if there was actually no electoral corruption taking place. All of thissuggests that the costs of petitioning were high enough relative to the benefits that adjudicatory
error would have contributed to high corruption rates.

4

Partisanship and Adjudicatory Error

In Section 2 we provided examples of MPs criticizing electoral corruption tribunals for being arbitrary and incompetent. The analysis in the previous section indicates that the high degree ofadjudicatory error implied by these critiques would have encouraged parliamentary candidates toengage in vote buying and other corrupt practices. It has never been systematically shown, how19

For example, one of John Stuart Mill’s suggested reforms (not adopted) was to provide public compensation for
petitioners whose corruption charges are upheld (HC Debs, 14 July 1868, Col 1176). Based on hearings evaluating
the effects of the reforms, it does not appear to be the case that judicialization reduced costs. See Select Committee
on Corrupt Practices Prevention and Election Petitions Acts, Report, 28 May 1875, HC 202 1875.
20
HC Debs, 21 May 1868, Col 667. Approximate value in current pounds is about 70 times higher.

15ever, that there was anything particularly wrong with the decisions of these corruption tribunals,
nor that any of their shortcomings were due to their constitution rather than e.g. to the difficultyof determining guilt in a corruption case. In this section we carry out the first systematic analysis
of a new dataset of Victorian electoral corruption trials and provide evidence that they sufferedfrom a particularly political type of adjudicatory error.
We show that the outcome of petition trials depended strongly on whether the tribunal hearing
the case was majority-Liberal or majority-Conservative. In particular, although Liberal and Conservative tribunals should have heard very similar cases, they differed sharply in their conviction
rates in a way that strongly suggests pervasive favoritism towards defendants of one’s own party.
These patterns provide prima facie evidence of error: put bluntly, if a Liberal tribunal would finda given defendant guilty and a Conservative tribunal would find him innocent, then even without
knowing the correct outcome we know that one of those tribunals is wrong. We also show that thispartisan error was lower in the set of cases heard by judges in the period after 1868.

4.1

Measuring error from case outcomes

As noted above, it is impossible to directly measure the rate of error in a set of rulings because
there is no way to know which defendants were actually guilty and which ones were innocent. We
therefore adopt an indirect approach that infers a lower bound on adjudicatory error by observing
partisan differences in conviction rates on similar sets of cases.
To motivate our approach, suppose that a sample of cases is randomly assigned to be heard byeither Tribunal A or Tribunal B, and suppose further that the conviction rate for cases heard by
Tribunal A is RA = .25 while the conviction rate for cases heard by Tribunal B is RB = .75. What
proportion of cases were wrongly decided? Given the randomization, in expectation the true rateof guilt among defendants is the same in the two sets of cases. In the most optimistic scenario,
then, the average error rate across tribunals was |.25 − .75|/2 = .25: if the true rate of guilt R is
16

Figure 2: Using variation in conviction rates to infer best-case error rates
Tribunal A

Tribunal B

RB
error

RA

=

RB

error

RA

Note: For each tribunal P ∈ {A, B}, the true rate of guilt among defendants is RP and the conviction rate is RP .
If RA = RB ≡ R, then across all possible R a best-case estimate of the average error rate between the two tribunals
is |RA − RB |/2.

.5, for example, then in the best case every conviction by Tribunal A was correct and 25% of its
defendants were wrongly acquitted, while every acquittal by Tribunal B was correct and 25% of
its defendants were wrongly convicted. (Figure 2 illustrates this situation.) As a general matter,under the assumption of an equal rate of guilt in cases heard by tribunals A and B, the best-caseaverage error rate across the two tribunals is |RA − RB |/2.21
To begin to apply this idea to our setting, consider Table 2, which reports the conviction rates
for Liberal and Tory defendants separately according to whether their case was heard by a Liberalor Tory tribunal.22 Suppose for now that Liberal defendants whose cases were heard by Liberal
21

Note that our calculation of the best-case average error rate does not require the two types of tribunals to beequally biased. Given conviction rates of .25 and .75, the best-case error rate is .25 as long as the true rate of guilt
is between .25 and .75.
22
We gathered data on election petition trials from a number of sources. Throughout the period we examine, theHouse of Commons published occasional reports of petition trials taking place over a certain period; these reports
can be found in the digitized House of Commons Parliamentary Papers, http://parlipapers.chadwyck.co.uk/.
For the period from 1852 to 1868, the reports included the principal information we needed (name of defendant,
composition of tribunal, case outcome); for the period between 1840 and 1852, we augmented the listings of petitions
with information from reports on individual petitions published in the Parliamentary Papers and announcements of
the assignment of tribunals published in the Journal of the House of Commons. For background on the defendants
and tribunal members, we draw from a database on the 19th century House of Commons that we have assembled

17

Table 2: Proportion of defendants losing seat by party of defendant and tribunal, 1840-1868

Liberal defendant
Tory defendant

Liberal tribunal
31/82 (0.38)
29/43 (0.67)

Tory tribunal
30/71 (0.42)
16/60 (0.27)

tribunals were just as likely to be guilty of corruption as those whose cases were heard by Torytribunals, and that the same holds for Tory defendants. (We justify this assumption below.) Whatis most striking about Table 2 is that the proportion of Tory defendants who were convicted depends
hugely on whether the case was heard by a Liberal tribunal or a Tory tribunal (and the differencein proportions is statistically significant, p < 0.01). The difference for Liberal defendants goes in
the opposite direction but is smaller (and not statistically significant). The data appears consistent
with allegations of partisan favoritism in tribunals’ rulings in the sense that Liberal tribunals havea higher conviction rate than Tory tribunals only when they face a Tory defendant, and vice versa.
What do these proportions tell us about the prevalence of error in petition outcomes? Following
the logic above and assuming the same true rate of guilt in cases heard by Liberal and Tory tribunals,
we can estimate the best-case error rate in cases against defendants of a given party as|RT − RL |
,
2

(5)

where RT and RL represent the conviction rates by Tory and Liberal tribunals, respectively. We
define this object as the Minimum Partisan Error (MPE). Under the assumption that the true
rate of guilt is the same in cases heard by Liberal and Tory tribunals (at least conditional on
defendant party), the MPE provides a best-case estimate of the component of adjudicatory errorthat is systematically related to the partisanship of the tribunal, whether because of favoritism,
differences in doctrinal approaches, or other factors.
from the work of Craig (1977; 1989) and other sources.

18

Before continuing, we stress that partisan error is related to but distinct from partisan favoritism
or partisan bias. “Partisan error” denotes a situation in which tribunals of different partisan
majorities treat similar defendants differently; under the assumption that all acts can be classified
as either legal or illegal, there must be adjudicatory error if the same acts are treated differently
by different classes of tribunals. “Partisan favoritism”, by contrast, denotes a situation in which
tribunals treat similar defendants differently based on whether the tribunal and the defendant comefrom the same political party. For example, if Liberal tribunals convicted 90% of both Liberal andTory defendants while Tory tribunals convicted 10% of both Liberal and Tory defendants, then wewould have considerable evidence of partisan error (again assuming the tribunals heard comparable
cases) but no real evidence of partisan favoritism.23
The MPE is only a meaningful indicator of adjudicatory error if it is reasonable to assume that,at least conditional on covariates, the true proportion of guilty defendants is the same in cases
heard by tribunals of different partisanship. Is that assumption reasonable in this case? We argue
that it is reasonable because of the highly unpredictable, if not random, way in which tribunals
were assigned to cases. When the House of Commons was convened following an election, losing
candidates had two weeks to file a petition; the petitions were then reviewed and an official list was
released, with the petitions listed in the order in which they had been approved (Warren, 1853).
Only then, when the order was fixed, were tribunals assigned to each case, following the alternation
procedure mentioned above.24 It would have been very difficult for a petitioner to arrange to havehis petition placed e.g. fourth on the list, especially considering that petitions were occasionally23

As suggested by Table 2, we find strong and robust evidence of partisan favoritism or bias in electoral corruption
trials. We emphasize error in this paper in order to maintain a focus on how partisan adjudication affected deterrence.
24
Each tribunal was composed of two MPs from each party plus a chairman whose party generally alternated as thepetitions went down the list. This convention was described in 1844 by Serjeant Digby Wrangham, a former MP who
often represented parties in election petition trials, before a committee inquiring into the election petition process.
Asked how he recommended tribunals should be constituted, he replied that “I should be disposed much rather toname them out of a certain panel by chance, than name them by taking one from each party, as I understand tobe the course now, and a Chairman either alternately or not strictly alternately, but taken from either party” (Parl.
Papers 1844, 373, pg. 59). That the Chairman’s Committee generally (but not strictly) followed this convention isindicated by comparing the party of the chairman assigned to each petition in a given year with the ordered list ofpetitions announced at the end of the petition submission period.

19rejected on technical grounds or withdrawn before the final petition list was announced.25 This
unpredictability implies that Liberal and Tory tribunals heard similar kinds of cases and thus, inthe absence of error, should have convicted a similar proportion of defendants, at least conditionalon the defendant’s party. As evidence for this, Table 6 in Appendix B compares characteristics ofcases and defendants assigned to Liberal and Tory tribunals, showing that (conditional on defendant
party) very few of these characteristics differ significantly.
It is worth emphasizing the importance of the quasi-random assignment of cases to tribunals inthis setting. In the presence of partisan favoritism and predictable assignment of cases, we would
expect cases heard by Liberal and Tory tribunals to differ sharply: a Liberal petitioner might sue
a Tory MP based on weak evidence if he knew he would face a Liberal tribunal, but not if he knew
he would face a Tory tribunal, with the result that case quality would be systematically related totribunal partisanship (conditional on defendant partisanship). In that situation, it would be almost
impossible to learn anything about error, bias, or anything else merely from studying conviction
rates. (For example, in his study of electoral petition cases in the U.S. House of Representatives,
Jenkins (2004) observes that the cases brought against majority-party congressmen were stronger
than those brought against minority-party congressmen, with the result that bias cannot be inferredfrom conviction rates.) The case assignment procedure used in Victorian Britain thus creates anunusual opportunity to study the relationship between adjudication and electoral corruption.

4.2

Estimates of partisan error

Table 3 reports marginal effects from logistic regressions of the form

convicti = β0 + β1 ToryDefendanti + β2 ToryTribunali + β3 ToryDefendanti × ToryTribunali + i , (6)25

Occasionally, petitions were also withdrawn after a committee was assigned to a case. This could in principle
lead to a tendency for unobserved case quality to be correlated with partisanship, for example if petitioners tended
to withdraw weak cases after being assigned to a non-copartisan. Table 2 suggests that this was not the case: cases
against MPs of a given party were more likely to be heard by committees of that same party, which is the oppositeof what we would expect if petitioners withdrew when they faced an unfriendly committee.

20

Table 3: Conviction probabilities as a function of defendant and tribunal partisanship, 1840-1868(1)
0.277∗∗(0.093)(2)
0.269∗∗(0.092)(3)
0.259∗∗(0.1)(4)
0.249∗(0.1)

Tory tribunal

0.042(0.073)0.044(0.075)0.042(0.074)0.045(0.075)Tory defendant ×Tory tribunal−0.435∗∗(0.133)−0.449∗∗∗(0.134)−0.427∗∗(0.133)−0.438∗∗(0.144)

256

256
X

256

0.109∗∗
0.001

0.112∗∗
0.001

256
X
X
0.11∗∗∗
0.000

Tory defendant

N
Election covariates?
Defendant covariates?
Min. partisan error
p-valueX
0.107∗∗
0.001

Note: Marginal effects are shown for logistic regressions in which the dependent variable is a 1 if the defendant isconvicted and 0 otherwise. Election covariates include the number of electors, an indicator for borough constituencies(cf. county constituencies), indicators for England, Ireland, Scotland and Wales, and a measure of competitiveness(the effective number of candidates divided by the district magnitude). Defendant covariates include an incumbency
indicator, age, an indicator for whether the MP had previously spoken in parliament, and an indicator for whether
the MP had held a cabinet office. Minimum partisan error measures the magnitude of the difference in conviction
rates between tribunals of different partisanship, conditional on defendant party. The p-value refers to a test of thenull hypothesis of zero partisan error and is calculated via permutation inference as described in the text. Guide tosignificance codes: ∗∗∗ indicates p < .001; ∗∗ indicates .001 < p < .01; ∗ indicates .01 < p < .05; and † indicates.05 < p < .1.

where the dependent variable is a binary variable (1 if the defendant was convicted, 0 otherwise)
and the other variables indicate defendant and tribunal partisanship. In columns (2)-(4) we add
covariates for the case and defendant. (Covariates are listed in Table 6 in Appendix B.) The implied
conviction probabilities from column (1) are, not surprisingly, quite close to the raw proportions inTable 2. The estimates barely change when we add covariates in columns (2)-(4), which provides
additional evidence that case characteristics were largely independent of the partisanship of thetribunal.
At the bottom of Table 3 we report our estimates of Minimum Partisan Error (MPE) alongwith p-values generated through permutation inference. In particular, given the regression equation

21

above (Equation 6), we estimate the overall MPE as

MPE =|β2 | + |β2 + β3 |
,
4

(7)

which is the average of the MPEs across the two parties.26 For statistical inference, we simulate thesampling distribution of the MPE under the null hypothesis of no partisan effects by repeatedly
permuting the vector of tribunal partisanship indicators and estimating the implied MPE; thereported p-value indicates the proportion of simulations producing an MPE larger than the observed
value.
Across specifications, the estimated MPE is about .11, indicating that at least 11% of cases(averaging across the two parties) were incorrectly decided due to inconsistencies between Liberal
and Tory tribunals. The way we have defined MPE, this error could in principle come simply
from differences in the legal standard applied by tribunals of different partisanship: it could be, forexample, that tribunals of one party systematically applied a higher standard of evidence and thus
convicted a lower proportion of defendants regardless of the defendant’s party. Our findings suggestthat partisan error in this context was not so innocuous. Contrary to what many contemporary
politicians and outside observers claimed,27 MPs’ partisan loyalties appear to have colored their
judgment in electoral corruption trials; this partisan favoritism contributed to the unreliability of
the adjudication system and thus encouraged electoral corruption.
26

Following convention, we estimate regression coefficients using logistic regression; we then estimate marginal
effects (reported in Table 3) and use these in our estimates of MPE. Results are essentially identical using a linear
probability model and directly inserting regression coefficients into Equation 7.
27
For example, speaking in debate on the Parliamentary Elections Act, Edward Pleydell-Bouverie, Liberal MP for
Kilmarnock, stated of the institution of election petition committees, “It was not alleged by anybody well acquainted
with the facts that it was partial; during the last twenty years I have been Chairman of a very great number of such
Committees, and I have a strong opinion that they did their best to try the question submitted to them with thegreatest impartiality. Indeed, I believe their decision was very often against the party feeling of the majority. . . .
Speaking on the whole, there was no party colour in their decisions” (HC Deb, 6 July 1868, Col 723). See also the
speech by Philip Wykeham-Martin (“If I were to be tried for my life I should be perfectly satisfied to trust my case in
the hands of a Committee of that House”), as well as the address to the Juridical Society by F.D. Maurice (Maurice,1871).

22

5

Did Judicialization Deter Corruption?

The Parliamentary Elections Act of 1868 transferred the responsibility of hearing election petitions
from the House of Commons to the courts. Moving jurisdiction to the courts addressed many ofthe perceived shortcomings of the old system. Judges could hold trials “on the spot” and without
waiting for the House of Commons to convene following an election; judges also of course far
exceeded MPs in their knowledge and experience of handling evidence, following legal procedure,
and applying statute and legal precedent to particular cases. Of particular relevance to the foregoing
discussion of partisan error, judges were also not sitting politicians with a direct political interest in
the proceedings. In conjunction with the formal analysis of Section 3, all of this suggests that theParliamentary Elections Act helped to reduce electoral corruption by making adjudication moreaccurate.
In this section, we marshal two kinds of more concrete evidence suggesting that judicialization infact led to more accurate adjudication and thus helped to contain corruption in Victorian Britain.
We again resort to indirect methods, both because we do not observe corruption directly andbecause other reforms that probably reduced corruption were implemented around the same time
(most importantly, the Second Reform Act in 1867 and the Ballot Act in 1872).

5.1

Judicialization and partisan error

The judges who heard election corruption trials after 1868 were not sitting politicians, but almost
all of them had known political leanings. Many of them had in fact served in the House of Commons
or stood as a parliamentary candidate. Indeed, one of the criticisms of the Parliamentary Elections
Act in 1868 had been that it would do little to alleviate partisan favoritism because judges had
partisan allegiances just as MPs did.28
28
For example, Edward Pleydell-Bouverie, Liberal MP for Kilmarnock, argued that “Judges are not angels, but
are – like other men — liable to be influenced by their political feelings in political matters” (HC Debs, 21 May 1868,

23

Table 4: Proportion of defendants losing seat by party of defendant and tribunal, 1868-1880

Liberal defendant
Tory defendant

Liberal tribunal
24/55 (0.44)
15/35 (0.43)

Tory tribunal
6/11 (0.55)
4/13 (0.31)

To get a sense of whether judges were in fact less partisan in their rulings, we extend theanalysis of the previous section into the post-1868 period.29 As in the previous section, it isimportant to establish that the cases that Liberal and Tory judges heard were comparable, at leastconditional on covariates. Fortunately, the system by which cases were assigned to judges was
similarly unpredictable ex ante, which helps to ensure that the true proportion of guilty defendants
was similar across judges. Under the new system, as under the old system, losing candidates had
two weeks after an election to file petitions; each case was then assigned to one of three superior
court judges30 according to the order in which it stood on the final list of petitions. Consistent witheffectively random assignment of judges to petitions, we again find that candidate characteristics
appear to be balanced across cases assigned to Liberal and Conservative judges, as reported inTable 6 in Appendix B.
Table 4 reports the conviction rates for cases heard by judges between 1868 and 1880 in thesame format as Table 2. The raw estimate of Minimum Partisan Error implied by these conviction
rates is just under .06, or around half of that for the earlier period. To take account of covariates
and test for a difference in minimum partisan error between the two periods, Table 5 extends theanalysis of Table 3 to incorporate this data. In each regression model we include indicators forthe partisanship of the defendant and tribunal (whether of MPs or judges) and (in models (2)-(4))
Col 684). John Stuart Mill stated in debate that he “was far from being disposed to place implicit confidence in theJudges” because he “could not forget that they had been politicians, and that they were sometimes thought to bepoliticians still” (HC Debs, May 21, 1868, Col 683).
29
We assign partisan labels to judges based on their prior political service and authoritative biographical accounts
when possible; in the few remaining cases we use the party of the government appointing them.
30
The judges were puisne judges drawn from the Queen’s Bench, the Court of the Exchequer, and the Court ofCommon Pleas. From 1880 the cases were heard by two judges; in cases from that year, we code the partisanship as
neutral when judges from different parties were assigned to a single case.

24

Table 5: Conviction probabilities as a function of defendant and tribunal partisanship, 1840-1880(1)0.285∗∗(0.095)(2)0.275∗∗(0.097)(3)
0.263∗∗(0.095)(4)0.251∗∗(0.096)Tory tribunal

0.043(0.076)0.045(0.078)0.043(0.075)0.045(0.078)Tory defendant ×Tory tribunal−0.448∗∗∗(0.134)−0.457∗∗(0.144)−0.435∗∗(0.139)−0.441∗∗(0.14)

Tory defendant ×
post-PEA−0.276∗(0.137)−0.285∗(0.135)−0.256†(0.137)−0.249†(0.141)Tory tribunal ×
post-PEA

0.156(0.172)

0.093(0.164)0.162(0.166)0.113(0.176)Tory defendant × Torytribunal × post-PEA

0.181(0.235)0.298(0.254)0.178(0.237)0.28(0.254)

402

402
X

402

0.109∗∗

0.112∗∗

0.001
0.063
0.434
−0.045∗
0.035

0.001
0.038
0.741
−0.074∗∗
0.002

402
X
X
0.11∗∗∗
0.000
0.04
0.728
−0.07∗∗
0.002

Tory defendant

N
Election covariates?
Defendant covariates?
Min. partisan error: MPs
p-value
Min. partisan error: judges
p-valueDiff. in min. partisan error
p-valueX
0.107∗∗
0.001
0.062
0.454
−0.045∗0.039

Note: See notes to Table 3. All covariates are interacted with the post-PEA indicator, which identifies cases heard
after judges assumed responsibility for corruption trials in 1868.

a set of covariates. All terms in the regression are interacted with an indicator identifying theperiod in which judges heard cases (“post-PEA”), such that we effectively fit separate models forthe two periods. At the bottom of each table we report the implied Minimum Partisan Error forthe period in which MPs heard cases (again, consistently around .11 and strongly significant) andthe period in which judges heard cases (around .05 and not statistically significant). We also report
the estimated difference between the two MPE estimates; across models, the drop is estimated at
between .05 and .07 and is significant at the .05 level in all cases.

25

As noted above, many other factors changed between the period when MPs heard petition trials
and the period when judges heard petition trials. Most notably, judges took over exactly when theelectorate was expanded by the Second Reform Act, and the secret ballot was introduced just a
few years later; these measures reportedly changed the nature of electioneering in ways that likely
affected the kinds of cases judges faced as well as the potential for error in deciding those cases.31
Due to these changes, we cannot be sure whether the reduction in partisan error we observe isdue to changes in who decided the cases or in what kind of cases they faced. It seems likely,
however, that differences between judges and MPs contributed to this drop in error. Judges had
many advantages over the MPs who had previously heard electoral corruption trials, including theadvantage of holding these trials more promptly and locally than had previously been the case.
Despite the political background of many of these judges, they also probably faced less politicalpressure to produce a favorable decision. We interpret our finding of lower partisan error in electoral
corruption trials after 1868 as evidence that, through some combination of these advantages, judges
issued more accurate rulings and thus helped to constrain electoral corruption.

5.2

Judicialization, petition rates, and conviction rates

An alternative way of assessing the reliability of judges as arbiters of election petitions is to examine
aggregate data on the volume of petitions filed and the outcomes of those trials. As indicated by
Figure 3, the petition rate (the proportion of competitive elections that resulted in a petition)
dropped substantially soon after judges assumed responsibility for these cases, while the conviction
rate (the proportion of petitions that resulted in a conviction) rose. This is the pattern one would
expect if, when judges took over responsibility from tribunals in the House of Commons, electoral
corruption trials became more effective at convicting guilty defendants and acquitting innocent
31

The transfer of jurisdiction also coincided with a change in the way costs were allocated in petition hearings:
judges tended to assign the legal costs to the losing party (Hardcastle, 1874, pg. 52). See Appendix A.2 for a discussionof how this change in the distribution of costs relates to our analysis.

26

Figure 3: Petition rate and conviction rates, 1840-1880

Conviction rate

0.8

1.0

0.15

Petition rate

0.6

0.10

●

●

●
●

●

●

●

●

0.4

0.05

●
●

●

●

●
●
●

0.0

0.00

●

0.2

●
●

1840

1850

1860

1870

1880

1840

1850

1860

1870

1880

Note: The left panel depicts the proportion of election contests (those with more candidates than seats) that resulted
in petition trials for each general election between 1840 and 1880. The right panel depicts the proportion of petitioned
MPs who were convicted.

ones.32 Most straightforwardly, making outcomes less arbitrary may have simply discouraged losing
candidates who had little or no evidence of the winner’s wrongdoing from filing a petition. In thepresence of a large random component to trial outcomes, a losing candidate with a weak casecould file a petition in the hopes of ending up with a favorable tribunal; improving accuracy would
discourage such petitions and, by eliminating some petitions in which the defendant was likely
innocent, increase the conviction rate.
32
The numbers suggest that candidates did not immediately respond to the new situation, as the petition rate
remained high and the conviction rate remained low in the 1868 election, the first one in which petitions trials
were heard by judges. As indicated by Stokes et al. (2013), the petition rate dropped even more drastically in thesubsequent period.

27

6Conclusion

This paper makes three primary contributions. First, it clarifies the relationship between adjudicatory error in electoral corruption cases and the equilibrium level of electoral corruption in asetting where petitions are strategically filed. It shows that the intuition that adjudicatory error
undermines deterrence applies in such a setting as long as the cost of filing petitions is sufficiently
high. Second, it analyzes new data on petition outcomes to highlight a strong partisan component
to the decisions made by tribunals of MPs in the period 1840-1868; in conjunction with the formal
analysis and evidence of high petition costs in this period, our findings of partisan error suggest that
self-policing by MPs contributed to the pervasiveness of electoral corruption in Victorian Britain.
Finally, this paper provides evidence that judges were more reliable as arbiters of election petition
cases, which suggests that delegating responsibility for these trials to judges may have reduced corruption in the last three decades of the nineteenth century. Like others, we find that independent
regulation of political competition better constrains corrupt practices; our general contribution has
been to solidify a theoretical basis for this claim and to empirically document it in a historicallyimportant setting.
The notion that election disputes should be resolved in the legislature (as embodied in the
19th-century House of Commons) was once embraced in many countries as part of an assertion of parliamentary supremacy or separation of powers. The British House of Commons wasin fact the first national legislature to abandon “self-certification,” with similar reforms subsequently undertaken elsewhere (Lehoucq, 2002; Massicotte, Blais and Yoshinaka, 2004; Williams,
2009; Orozco Henrı́quez, 2010). Although some view self-certification as having been “discredited
beyond repair” (Mozaffar and Schedler, 2002, pg. 16), legislatures continue to play a role in deciding
election disputes in many countries (Massicotte, Blais and Yoshinaka, 2004); meanwhile, allegationsof partisanship and error persist even in settings where electoral governance has been delegatedto “independent” institutions (e.g. Hayward and Dumbuya, 1985; Mozaffar, 2002; Popova, 2006;

28

Hoglund, Jarstad and Kovacs, 2009; Herron, 2010). Thus the institutional context for regulating
electoral competition remains relevant.

29

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Appendix A.1: Analysis of Model
We solve the game from the end. After the election is held, the losing candidate has the opportunity
to sue. Denote by σ his belief that the winning candidate played D. (Recall that the candidates
never observe each other’s campaign actions.) The losing candidate i will file suit ifkσ(1 − θ) + 1 − σ θ > .
b(8)Equation 8 implies that the losing candidate will choose to sue as long as
k/b − θ≡ σ̃.
1 − 2θ

(9)∂ σ̃
2k/b − 1=∂θ(1 − 2θ)2(10)σ>Note thatwhich indicates that whether error makes the loser more or less ready to file suit depends on theratio of the cost of suing k to the benefit of winning a suit b: when k/b < 1/2, a higher degreeof error reduces σ̃ and thus makes the loser more ready to file suit (i.e. willing to file suit when
he is less confident of the defendant’s guilt); otherwise, the relationship is reversed and more error
makes the loser less ready to file suit.
We begin with pure-strategy equilibria. Based on Equation 8, if θ > 1 − k/b a losing candidate
will not choose to sue even when he knows the winner is guilty; given that the winner will neverbe sued, both candidates will play D as long as δ > d. Similarly, if θ > k/b a losing candidate will
choose to sue even when he knows the winner is innocent; given that the winner will always be
sued, the candidates will both choose to play C if
1/2 + d − δk
1 + δ(1 − b)(11)

1/2 + d − δ(1 − b + k).
1 − δ(1 − b)

(12)

θ<
and will both choose to play D ifθ>Assumption 1 requires that the RHS of Equation 12 be less than the RHS of Equation 11; when thisis met, there are parameter values for which both Equation 11 and Equation 12 are satisfied and thus
both equilibria exist for some θ > k/b. (When Assumption 1 is not met there are parameter values
at which neither condition is satisfied and asymmetric equilibria in which one player plays C andthe other plays D can be sustained.) In what follows we assume that Assumption 1 is met, whichrules out asymmetric pure-strategy equilibria; we also adopt Assumption 2, which eliminates thecomplication of multiple pure-strategy equilibria. (The basic point – that error invites corruption aslong as filing petitions is expensive and error is high – would hold if we dropped these assumptions,but equilibria would be more difficult to characterize.) We thus have two regions of pure-strategy
equilibria, as depicted in Figure 1: both play D when θ > 1 − k/b or Equation 12 is met; both play33

C if θ > k/b and Equation 12 is not met.
We now turn to mixed strategies. If θ < 1 − k/b and θ < k/b, then losing candidates want to sue
if they know that the winner played D but not if they know that the winner played C. The only
equilibrium for these parameter values (excluding the one in which Equation 12 is met) is a mixed
one in which candidates play D with some probability α and the losing candidate plays a randomizedsuing strategy. Because we are primarily concerned with the relationship between corruption andadjudicatory error, we focus here on equilibrium values of α, which in a mixed strategy equilibrium
are probabilities of playing dirty that induce the losing candidate to be indifferent between suingand not suing, conditional on his own electoral action.33 Using Bayes Rule, we can express thelosing candidate’s belief that the winning candidate played D, conditional on the loser having
played D, as
α
σD =
(13)
1 − 2δ(1 − α)and the corresponding belief conditional on the loser having played C asσC =α + 2δα.
1 + 2δα(14)

Note that σC < σD for all α < 1, which reflects the intuition that a candidate who cheats and thenloses is more likely to suspect the winner of cheating than one who does not cheat and then loses.34
Now, setting σD from Equation 13 equal to σ̃ from Equation 9 and solving for α, we derive an∗ that causes the losing candidate to sue with positive probability
equilibrium campaign strategy αD
only if he played Dσ̃(1 − 2δ)
∗
αD
=
(15)
1 − 2σ̃δ
and, setting σC from Equation 14 equal to σ̃ from Equation 9 and solving for α, we derive an∗ that causes the losing candidate to sue with certainty if heequilibrium campaign strategy αCplayed D and with positive probability if he played C
∗
αC
=

σ̃
.
1 − 2σ̃δ + 2δ(16)

∗ and losers sue with
Which MSNE obtains (one in which candidates play D with probability αD∗positive probability only after playing D, or one in which candidates play D with probability αCand losers sue for certain if they played D and with positive probability after playing C) will dependon parameter values, but for the purpose of relating α∗ to θ we can simply observe that both objects
33

For an MSNE with a given value of α, there is a corresponding suing strategy (a probability of suing for when
the loser was clean and another for when the loser was dirty only one of which is on the interior of [0, 1]) such thatthe candidates are ex ante indifferent between playing clean or dirty. The expressions for these suing strategies are
somewhat involved and are thus omitted here to focus on election corruption.
34
Put differently, Equations 13 and 14 indicate that, for a fixed prior probability of one’s opponent being dirty, acandidate who was dirty and lost is more likely to have faced a dirty opponent than a candidate who was clean and
lost.

34

are increasing in θ when k > b/2:

and

∗
∂αD
b(2k − b)(1 − 2δ)=2∂θ
b(1 − 2θ + 2θδ) − 2δk

(17)

∗
∂αC
b(2k − b)(1 + 2δ)
=
2
∂θ

b 1 − 2θ + 2δ(1 + θ) − 2δk(18)

We have thus characterized α∗ (θ) sufficiently to construct Figure 1, on which basis Proposition 1
was proven.

Appendix A.2: Alternative assumptions about costs
The model assumes that the only cost of a petition trial is paid by the petitioner; it further assumes
that this cost is paid by the petitioner whether or not he wins the suit. In reality, of course, boththe petitioner and the respondent sustained legal costs; furthermore, from 1868 the losing party
typically paid both sides’ costs (an arrangement known in law as the “English Rule”).
Alternative arrangements for assigning costs indeed affect the incentives facing the players, but
additional analysis indicates that the nature of the relationship between electoral corruption andadjudicatory error does not depend on how much it costs to be sued or whether costs are paid by
the loser. To see this, first consider the possibility that there is a cost to being sued. Obviously,
such a cost would not affect the decision to sue, conditional on the losing candidate’s belief about
the winner’s probability of being corrupt. This means that where θ > 1 − k/b losing candidates
will always sue, and where θ > k/b they will never sue, regardless of the cost of being sued. It
also means that the probability of the winner having played D that makes the losing candidate
indifferent between suing and not suing is given by Equations 15 or 16 (depending on the loser’s
own electoral action), again regardless of the cost of being sued. Thus the general arrangement ofequilibria as in Figure 1 does not depend on the cost of being sued. To be sure, the cost of beingsued does affect the relative attractiveness of playing C or D: in an equilibrium where the election
winner has a positive probability of being sued, playing D becomes less attractive if being sued iscostly, because winning effectively becomes less valuable. This means that the condition separating
the PSNE in which both play and C from the PSNE in which both play D (which is given by
Equation 11 for the case where being sued is costless) does depend on the cost of being sued, as
does the equilibrium level of corruption in a MSNE. But the general arrangement of equilibria will
be as in Figure 1, and the relationship between adjudicatory error and the rate of corruption will
be as described in Proposition 1, even if there are costs to being sued.
We can make a similar point about the comparison between the “English Rule” (loser pays legal costs) and the “American Rule” (each side pays own legal costs). From the perspective of theloser, a move to the English Rule can be thought of simply as an increase in both k (the losing
35

candidate’s cost of filing a petition) and b (the benefit he gets if he is successful). To reflect the
English Rule, think of k (the cost of filing a petition) as kL + kW , where kL is the total cost of
the proceedings to the losing candidate (petitioner) and kW is the same for the winning candidate(respondent), and think of b as b̃ + kL + kW , where b̃ is the actual benefit of winning the suit (interms of probability of winning the seat and other benefits). So we can conceive of the English Ruleas a system in which you pay both sides’ legal costs to file a suit, but you get those costs paid back(plus whatever benefit comes with winning the lawsuit itself) if you win. From the perspective ofthe loser, then, the English Rule and the American Rule imply different magnitudes of the costand benefit but do not affect the nature of the analysis, and thus by the arguments made in theprevious paragraph we expect the equilibria that obtain to be more or less the same. From an ex
ante perspective, the way in which costs are allocated indeed affects incentives to be corrupt or notcorrupt, but it does not qualitatively affect the way adjudicatory error and corruption are related.

36

Appendix B: Balance tests
Table 6: Balance tests by party of defendant
Party of petitioned MP:
Conservative
LiberalParty of tribunal:
Con.
Lib.
p-val.
Con.
Lib.
1840-1868 (Cases heard by MPs in the House of Commons)
Borough
0.93
0.95
0.67
0.92
0.94
England
0.97
0.88
0.10
0.77
0.85
Electors (k)
1.60
2.93
0.04∗
1.34
2.08
Competitiveness
1.85
1.81
0.48
1.71
1.78
†
0.20
0.37
0.05
0.30
0.30
Close election?
Year
1852.97 1851.47
0.33
1853.93 1854.24
Age of MP
48.67
41.07
0.00∗∗∗
46.39
43.04
Incumbent?
0.42
0.30
0.24
0.49
0.50
Years served
4.27
3.14
0.35
4.79
3.61
26.30
6.95
0.14
31.89
39.71
Speeches madeWords (k)
10.90
1.31
0.09†
9.00
21.55
Obs.
60
43
71
82
1868 - 1880 (Cases heard by judges of the Superior Courts)
Borough
0.83
0.97
0.10
1.00
0.87
England
0.83
0.79
0.77
0.90
0.71
3.04
5.14
0.19
4.36
7.85
Electors (k)Competitiveness
1.91
1.91
0.97
1.93
1.87
0.25
0.09
0.16
0.30
0.15
Close election?
Year
1869.33 1869.88
0.55
1868.20 1870.65
Age of MP
44.83
46.41
0.71
48.10
48.08
Incumbent?
0.17
0.35
0.24
0.70
0.56
1.58
2.74
0.54
7.40
5.94
Years served
Speeches made
0.58
7.29
0.26
24.40
53.60
Words (k)
0.31
2.03
0.29
5.82
21.39
Obs.
13
51
11
74

p-val.
0.58
0.21
0.03∗
0.16
0.95
0.79
0.07†
0.93
0.23
0.81
0.50

0.22
0.22
0.26
0.37
0.28
0.01∗
1.00
0.41
0.65
0.54
0.48

Note: Each p-value corresponds to a test of the null hypothesis of no difference in the mean value of the covariate
between cases assigned to Conservative and Liberal tribunals.

37