Lord Diplock in
Miller urged us to use 'conduct of the accused' rather
than "actus reus"
'actus reus' is derived from Coke's Institutes "et actus non
facit reum, nisi mens sit rea,"
By incorrectly using "reus" as an
adjective instead of a noun, the phrase is likely to mislead, because it
suggests that some positive act is required. Whereas a failure or
omission to act can give rise to criminal liability.
said that it would be better that we avoid bad Latin and instead to think
and speak about the conduct of the accused and his state of mind at
the time of that conduct, instead of speaking of actus reus and
Smith  HL
"Strictly speaking, though in almost
universal use, it derives, I believe, from a mistranslation of the Latin
aphorism: "Actus non facit reum nisi mens sit rea."
Properly translated, this means
"An act does not make
a man guilty of a crime, unless his mind be also guilty."
It is thus not the actus which is
"reus," but the man and his mind respectively. Before the understanding of
the Latin tongue has wholly died out of these islands, it is as well to
record this as it has frequently led to confusion."
act does not make a person legally guilty unless the mind is legally
Contrasting judicial positions on the
usefulness of using the terms actus reus and mens rea.
Court of Appeal in Singh (Gurdev) v The Queen  CA
"...the division of crimes into actus reus
and mens rea is sometimes extremely helpful. In these
particular circumstances it does nothing except cloud the issue."
Lynch v DPP for Northern Ireland 
Simon of Glaisdale
"[The terms actus reus and mens
rea] have, however, justified themselves by their usefulness; and
I shall myself employ them in their traditional sensesónamely
actus reus to mean such conduct as constitutes a crime if the
mental element involved in the definition of the crime is also present
(or, more shortly, conduct prohibited by law); and mens rea
to mean such mental element, over and above volition, as is involved
in the definition of the crime."
The mental element in actus reus
sometimes contains a mental element
In some assaults, foreseeing the risk of harm is a mental
Foreseeability is part of
is part of the actus reus.
Therefore, the actus reus of some assaults
requires a mental element to be proved by the prosecution.
"Actus non facit reum nisi mens sit rea"
actus = act
reum (reus) = liable
A man is not liable for his acts alone, but only if he
acts with a guilty mind.
Examples of mental elements in
of Theft Act offences
includes "appropriation" and "possession", these require a mental element.
"Appropriation" and "possession" are recognised to be
terms used in the actus reus of offences and yet necessarily
involving some mental element in the accused.
Professor Glanville Williams has stated that some crimes,
including attempts, were examples of crimes in which:
"The act constituting a crime may...take its criminal colouring entirely
from the intent with which it is done."
The act "to take" or "to give" cannot be done by
accident, yet are part of the actus reus.
There is a mental
element implicit in the actus reus of any offence of unlawful
Therefore the usual distinction between the mental element and the
external manifestation of a crime can be difficult to apply in cases where
the crime is one of 'possessing', 'permitting', 'keeping',
'appropriating', etc, because these terms simultaneously import both
mental and physical elements.
D does not possess
something, which, unknown to him, has become stuck to the sole of his shoe
or the blade of his penknife Warner v Metropolitan Police Commissioner
 & Marriott . But, he may possess a controlled
drug without realising what it is that he possesses.
The correct legal
concept of possession involves both the actus reus of possession
and a state of mind, the
animus possidendi, which can only be a part of the mens rea.
In practice, the
animus possidendi is treated as if it were an element of the actus
Animus possidendi must always be proved by the prosecution,
whereas the burden of proof in respect of other mens rea elements
is placed on the defence.
Causing an affray, that is causing terror to others by
fighting, requires that the fighting be deliberate, and is part of the actus
reus, Taylor v DPP 
Thus, the Court of Appeal in R v Jones was content
to define the actus reus of affray as "fighting or the show of
"Going equipped" (To have with one any instrument for use
in a burglary, theft or cheat outside of one's place of abode). Section 25
of the Theft Act 1968.
The external conduct may be carrying a screwdriver.
If we ignore the question "What did D intend to use it for?" (that is his
purpose) we are left with entirely innocent behaviour; carrying a
screwdriver in the street.
The actus reus exists only if the
purpose of an otherwise neutral object - the screwdriver - that the
accused possesses is that he intends it to be used in for one of the
criminal purposes mentioned.
"Carrying an offensive weapon in a public place"
expresses the actus reus of section 1 (4), Prevention of Crimes
An offensive weapon turns on the accused's intention to
injure another with it. It is this intention that translates an umbrella
or hammer into an offensive weapon and hence allows us to describe the
conduct as prohibited.
However, the actus reus is not holding an umbrella
or hammer; it is carrying an offensive weapon R v Petrie .
"Attempt" means D was trying to create the actus reus
of the crime.
D is only is attempting to commit the crime (the actus
reus of attempts) if his purpose is the attainment of that crime.
Sweet v Parsley 
The ratio decidendi of Sweet v Parsley was not
that an essential of liability, mens rea, was absent but that there
was no actus reus.
What was prohibited was "running a cannabis den" and Miss
Sweet was doing nothing of the sort.
"Running" involved knowledge of the function given to the
premises, this is part of the actus reus.
Lord Diplock said that the knowledge or purpose of the
accused was a requisite of both parts of the actus reus - the
"running" and what was "run".
Impersonation or "Personation" occurs by presenting
oneself as another.
This offence can be committed by pretending to be a
juryman, policeman, voter or many other persons.
The actus reus may be brought about accidentally
or otherwise innocently.
Impersonation is the endeavour to appear as another. The
crime of "impersonation" requires the deliberate pretence to be another,
not merely causing another to mistake one for someone else It does not
dependent on convincing someone that one is the person one is pretending
The actus reus of "impersonating a police
officer," (section 52 (2), Police Act 1964), involves D having a
Rape "by inducing a married woman to have sexual
intercourse by impersonating her husband" (section 1 (2) Sexual
Offences Act 1956) involves the prohibited conduct of trying to appear
as her husband.
Indecent assault only occurs when V has been sexually
The crime occurs when there is an assault in
"circumstances of indecency."
This indecency forms part of the actus reus of the
offence in the same way that causing actual bodily harm is part of the actus
reus of assault occasioning actual bodily harm.
"Circumstances of indecency" turn an assault into an
indecent assault when D's purpose in the assault is a sexual purpose.
In R v Sutton,  D photographed children in
pornographic positions. He touched the children in order to arrange the
poses. If his touching had been indecent (sexual) there would have been a
sexual assault. But his intent was merely to arrange the subjects.
Only if the assault has sexual significance to the
accused has the victim been indecently assaulted.
If one of the boys had thought the touching was sexual,
he would have misunderstood the situation: he would not have been touched
sexually "by accident."
The sexuality is part of the actus reus, not
merely ulterior intent, as the crime refers to a distinct kind of assault.
This conduct is now
covered by the
Sexual Offences Act 2003.
"False imprisonment" can depend upon D's beliefs.
If a constable,
genuinely and reasonably believed that V was guilty of an offence, V will not have been falsely imprisoned whether he has actually
committed an offence or not.
Whether imprisonment is
false or not will turn, usually, not only on mere subjective belief in the
legitimacy of the arrest, but also on the reasonableness of that belief.
This is certainly so
section 2 (2)-(7) Criminal Law Act 1967. But there still must
be genuine suspicion. If a PC arrests someone without suspecting him to be
guilty of an arrestable offence, he would be guilty of false imprisonment.
Hence, the existence of the actus reus turns on the accused's mind.
Harnett v Bond 
Harnett was classified as insane and kept in a mental institution managed
by Dr Adam.
Adam released Harnett on licence.
Harnett visited a Dr Bond, who decided that Harnett was insane, detained
Harnett in his office and arranged for Harnett to return to Dr Adam's
Harnett remained there for several years until he escaped and was judged
by two psychiatrists to be sane.
was clear that Dr Adam had believed Harnett to be mad throughout the time
of Harnett's incarceration.
Harnett sued the doctors for false imprisonment.
Viscount Cave LC:
"The leave of absence order authorises the medical officer [Dr Adam] to
retake the patient if the patient's mental condition requires it. If
this power is exercised negligently, it may be that there is a remedy;
but the negligence does not make the retaking unlawful, and the remedy
(if any) is by action for negligence and not by action for false
Hence, Dr Adamís
attitude to Harnett meant there had been no actus reus of false
imprisonment, either as a crime or as a tort.
The actus reus of theft includes appropriation.
"appropriation" and this concept revolves around D's attitude to another's
property that is, an assumption of the rights of the owner.
Professor Smith in The
Law of Theft:
"It is impossible to determine whether there has been an appropriation
without having regard to the intention with which an act was done."
Ignorance as to the lack of insurance is no bar to
conviction for permitting the use of an uninsured vehicle
There must be a conscious decision to allow another to
use the vehicle. So, if E believes that when D nods he is agreeing to E
driving D's car when, in fact, D was nodding in reply to another question,
D has not permitted E to drive his car.
In all cases involving "to permit," in the actus reus
the mind of the accused is involved.
In a certain type of manslaughter the actus reus
is not merely that V dies as a result of D's neglect, but that V was D's
had assumed responsibility for V. This only arises where D voluntarily
assumes the care of V.
R v Stone  the court inferred that the accused had assumed
responsibility towards his sister, it is apparent that the basis of the
court's decision was the existence of this voluntary assumption.
But the existence of this duty is a necessary part of the actus reus
Without it the conduct is not prohibited, and yet its existence
depends on the mind of the accused.
Two actus rea together with
one mens rea
Fagan v Metropolitan Police Commissioner
the accused accidentally parked his
car on a policeman's foot.
D realised what had
occurred and decided to leave his car on PC Morris' foot. Eventually he
moved it. He was convicted of assault. The activity of driving onto, and
remaining on the foot was the actus reus. D became liable for that
actus reus when he possessed mens rea.
The act of battery was
the external basis of the charge and spanned driving onto the foot to
removing the car but that liability proceeded from the joining of mens
rea to this.
Fagan's crime was the
single continuous assault. He could only be liable for that crime for
those periods during which he had mens rea.
If Fagan had, after
deciding to remain on the foot, wrongly thought his car had rolled off the
foot but on discovering the truth, decided to stay put, this second
occurrence of mens rea would not render him liable for a distinct
There has been a break
in mens rea, but the actus reus has continued uninterrupted.
Hence, Fagan would have committed the one assault at these two separate
times during which he had mens rea.
Thabo Meli  PC (South Africa)
a break in mens rea is irrelevant to the termination of the crime
"[Their crime is not
reduced] from murder to a lesser crime, merely because the accused were
under some misapprehension for a time during the completion of their
D's argument that there
was no contemporaneity of actus reus and mens rea was
rejected: the events were one transaction, during which malice
aforethought had existed.
The actus reus
stretched from the first blow to the eventual death. That was "the
As mens rea
existed at some time during that killing, they were liable for murder.
The emphasis is placed
upon the identity of a crime with its actus reus and the
requirement for liability that at some time during that actus reus
there is mens rea.
If mens rea existed at two separate times during the one killing, D
would only have committed one crime, although his liability for that
single crime would exist at those two periods of time.
Fagan and Thabo Meli
affirm the view that it is the actus reus that identifies the
existence of and duration of a crime.
The removal of a
mental element by voluntary consumption of alcohol (or drugs)
The criminal law sometimes holds that once the actus
reus is established liability is complete. An example is the defence
of voluntary intoxication.
If D is voluntary
intoxication and so is incapable of forming the necessary mens rea,
he will still be liable for that actus reus even though the crime
usually requires proof of mens rea. (This is not the case if the
crime charged is one of specific intent).
In R v Burns (1973)
CA, D a homosexual, was charged with indecent assault. He claimed that
he suffered a form of automatism resulting from the combination of
psychiatric disturbance and alcohol and awoke to discover his penis in
another man's mouth.
Indecent assault is not a crime of specific intent.
If Burns had been
unaware of his behaviour owing to intoxication, he would still be guilty
of indecent assault.
If the assault was not
deliberate and deliberately indecent, self-induced drunkenness is no
defence to indecent assault because no specific intent is required.
Indecent assault is not
a crime in which the accused must intentionally bring about the actus
reus or in which some ulterior intent must be proved for liability.
Hence, it is not a crime of specific intent. Whilst sexual purpose is a
necessary ingredient of this crime, it relates to the existence of the actus
reus, not the mens rea.
Burns was not relying
on a defence of intoxication, rather, if his actions were unconscious or
accidental, and thus not consciously sexual, there was no actus reus
and so there was no indecent assault.
There can be no
liability if there is no actus reus. Hence, a lack of sexual
purpose for whatever reason negates liability.
The need for conscious
sexuality means that the assault must be deliberate and there must be
Thus, the requirement
of deliberateness as to the assault is not a requirement of mens rea
but merely that the body contact be deliberate.