Why have the double jeopardy rule?
Why can't the prosecution appeal when the defence
Doesn't the double jeopardy rule let the guilty
we can make an exception for serious cases, such as murder,
there is compelling evidence of guilt subsequent to acquittal?
A possible exception?
About the author
The double jeopardy rule in UK law states that you cannot be tried for the
same crime twice. It is a rule that dates dates back to the 12th century under
Some people may find this rule a bit odd. After all, if new evidence turns
up that suggests the defendant acquitted in a trial was in fact guilty of
the crime for which he was being tried, then the rule means that person cannot
During March 2001, in the UK, a Law Commission report recommended for murder
cases, that if there is compelling new evidence, a case could be retried and
thus end the double jeopardy rule in murder cases. The Labour government indicated
that it would bring in legislation to give effect to this proposal in the
next parliamentary session.
It is the purpose of this essay to defend the double jeopardy rule, which
I regard as a fundamental cornerstone of the British justice system, the undermining
of which will lead to innocent people being harassed and jailed and to those
who do commit crime walking free.
Why have the double jeopardy
There are a number of reasons for the double jeopardy rule:
- The state has far more power to investigate and dig up evidence
than an individual.
This causes an asymmetry when an individual is prosecuted for an alleged
crime. The individual will not have the resources to go out and look for
the evidence that clears him and anyway, from the point of being charged,
may be held in custody whilst he waits for his trial. Thus, the individuals
ability to construct a defence against a charge is quite limited.
It is for this reason that the principle that you are innocent until proven
guilty has informed the development of many legal systems. Allowing repeated
trials of the same person for the same offence skews an already imbalanced
situation even further in the states favour.
We know that the justice system is fallible. Therefore we know that, even
if evidence is not really strong enough to convict, this may still happen.
Thus repeated trials of the same person for the same offence will increase
the probability of wrongful conviction. In murder cases, this means the
guilty party will walk free. Thus, both innocent people will suffer and
the perpetrators are free to offend again.
- Removing the double jeopardy rule opens up the possibility of
the state harassing an individual with repeated prosecutions for the same
If the state can prosecute someone repeatedly for the same crime, then this
makes the option of politically motivated prosecutions more attractive as
a means of harassing an individual whom the state does not like or of whom
they are suspicious. Since the state would determine the hurdle to be passed
for a repeat prosecution, and also has considerable powers to dig up (or
even invent) dirt, the situation becomes heavily loaded in the states
- Removing the double jeopardy rule means that the innocent accused
can never rest easy.
It is quite possible for an innocent person to be accused of a crime
and, as a result, they come to trial to trial. If the double jeopardy
rule goes then, after acquittal, an innocent person cannot rest easy in
the knowledge that no further prosecution can be brought for that accusation
and that they can get on with their life, without worrying about a further
trial for that crime.
- The double jeopardy rule encourages the prosecution to make as
strong a case as it can manage.
If there is only one chance for convicting a criminal, the prosecution are
under strong pressure to make the best case they can for convicting the
If there is the option of trying again should the conviction fail, then
when a crime is being investigated, once the police believe theyve
got their man, there is no pressure to investigate further to ensure the
strongest possible case is presented rather than one they think will be
This will reduce the quality of the prosecution cases and the quality of
police investigations, increasing the risk of catching and even convicting
the wrong man. Further, even when the authorities have the right man, the
chances of an acquittal will be increased, resulting in the accused going
free; at least until the police find new evidence and persuade the courts
to allow the case to be tried again.
Thus not only would more innocent people be jailed, but more guilty people
may go free as well as a result of removing the double jeopardy rule.
- Retrials after an acquittal may undermine
the presumption of innocence.
Another problem with allowing a retrial after an acquittal lies in preserving
the presumption of innocence. For example, if the men accused of the murder
of Steven Lawrence were to be tried again for that crime, it would be well
nigh impossible to find a jury that was not aware of the media coverage
of the original trial and, therefore, who may be biased against the defendants.
If the jury knows they are judging a retrial where what a judge has found
to be compelling, new evidence is available, the
jury may decide that they cannot judge that it wasnt compelling. Yet
had the evidence been presented at the original trial, there is no guarantee
it would have led to conviction. It is also likely that a retrial will become
a cause celebre, with a great deal of political and public pressure
for a conviction regardless of the strength of the evidence.
I believe these reasons give strong support for the
retention of the double jeopardy rule on grounds of civil liberties, justice
and effective crime fighting. The rule was not placed into the legal system
without good reason, and certainly should not be abolished without better
Why cant the prosecution
appeal when the defence can?
Some may say that it is unfair that the defence can appeal a conviction when
the prosecution cannot appeal an acquittal. Even if this were true, the reasons
given above would, in my opinion, outweigh this consideration. However it
is not unfair; indeed, the right of appeal on the part of a defendant derives
directly from the principle that the innocent should not be punished unless
proven guilty of a crime. A right of appeal against an acquittal cannot be
Doesnt the double jeopardy
rule let the guilty walk free?
In some circumstances, yes it may, simply because the courts are fallible.
However as we have seen above, removing the rule may cause more guilty people
to walk free, due to a decline in the quality of the investigations and prosecutions
(leading to fewer criminals being caught and convicted), caused by the reduced
pressure to present the strongest possible case at the first trial for each
This is not a simple case of balancing the risk of jailing innocent people
in a repeated prosecution for a crime against letting guilty people walk free
through not being allowed to mount a second prosecution. Anyone presenting
it in those terms is failing to take into account the factors mentioned earlier.
It should also be mentioned that, where someone makes a full confession after
being acquitted, there is the option of pursuing a perjury charge against
them; so it is not as if there is no sanction available should someone be
wrongly acquitted, and then they flaunt the fact that they were able to get
away with a crime.
can make an exception for serious cases, such as murder, where there is compelling
evidence of guilt subsequent to acquittal?
If anything, in a serious case, where the consequences of a wrongful conviction
or a wrongful acquittal are serious, the case for an exception to be made
is weakest. With serious crimes, it is most important that an investigation
and trial be performed with utmost care and thoroughnessmistakes could
cost lives and lead to innocent people being jailed for many years. Allowing
a repeat trial in such circumstances would lead to an incentive to hold back
evidence, or lines of inquiry, for a retrial.
Thus the double jeopardy rule is even more important than normal in such
cases, as it puts pressure on the prosecution and the investigators of a crime
to do their jobs to the best of their abilities, because they will not have
a second chance.
A possible exception?
Through discussing double jeopardy on usenet, it occurred to me that some
of the concerns raised about removing the double jeopardy rule can be addressed
if a new prosecution is allowed only when the
new evidence could not possibly have been presented at the original trial,
e.g. because the technology that uncovered the evidence was not available
at the original trial.
This proposal would ensure that the incentive to present the strongest case
at the original trial would remainthere would be no reason to hold back
evidence or lines of inquiry for a possible retrial. It does not address all
the concerns raised, e.g. the threat of a retrial hanging over the innocent
accuseds head, but it would acknowledge those who argue that when new
technology is developed we should be able to do a retrial, without increasing
the risk of a lower standard of evidence and more wrongful convictions and
However, there is still a problem left: namely that of preserving the presumption
of innocence, as decribed in point 5 above. In any
retrial involving new evidence, ensuring that no-one on the jury was aware
of the original trial, or is aware that the trial theyre judging is
a retrial, will be virtually impossible with high-profile cases and may be
very difficult otherwise. This consideration, along with the ongoing trend
in attacking civil liberties, makes me very reluctant to remove the double
jeopardy rule, even in such a rigourously tested manner, lest it become the
first stage in abolishing the rule outright or otherwise leads to injustice.
That a few guilty people may walk free because of double
jeopardy is, in my humble opinion, a small price to ensure
that crimes are investigated properly and that prosecutions
are conducted to the best of the abilities of the people
involved; and thus to make sure that, as far as possible,
justice is done, both in terms of catching those committing
crimes and ensuring the innocent are not wrongly imprisoned.
About the author
James Hammerton is a computer
scientist with a long standing interest in politics.
This article is copyright. You may distribute it freely so long as you acknowledge
my authorship of it.
James Hammerton, 2002