Dishonesty is to act without honesty. It is used to describe a lack of probity, cheating, lying or being deliberately deceptive or a lack in integrity, knavishness, perfidiosity, corruption or treacherousness. Dishonesty is the fundamental component of a majority of offences relating to the acquisition, conversion and disposal of property (tangible or intangible) defined in criminal law such as fraud.
English law 
Dishonesty has had a number of definitions. For many years, there were two views in English law. The first contention was that the definitions of dishonesty (such as those within the Theft Act 1968) described a course of action, whereas the second contention was that the definition described a state of mind. A clear test within the criminal law emerged from R v Ghosh (1982) 75 CR App. R. 154. The Court of Appeal held that dishonesty is an element of mens rea, clearly referring to a state of mind, and that overall, the test that must be applied is hybrid, but with a subjective bias which "looks into the mind" of the person concerned and establishes what he was thinking. The test is two-stage:
- "Were the person's actions honest according to the standards of reasonable and honest people?" If a jury decides that they were, then the defendant's claim to be honest will be credible. But, if the court decides that the actions were dishonest, the further question is:
- "Did the person concerned believe that what he did was dishonest at the time?"
The decision of whether a particular action or set of actions is dishonest remains separate from the issue of moral justification. For example, when Robin Hood robbed the Sheriff of Nottingham he knew that he was, in effect, stealing from the Crown, was acting dishonestly and would have been properly convicted of robbery. His argument would have been that he was morally justified in acting in this way but in modern legal terms this could only have been brought to the court by way of mitigation of sentencing and would not have affected the inference of dishonesty.[neutrality is disputed]
Where dishonesty is an issue in civil cases, the trend in English Law is for only the actions to be tested objectively and not to apply any test as to the subjective state of mind of the actor.
Theft Act 1968 
The Theft Act 1968 contains a single definition for dishonesty which is intended to apply to all the substantive offences. Yet, rather than defining what dishonesty is, s2 describes what it is not, allowing a jury to take a flexible approach, thus:
s2(1). A person’s appropriation of property belonging to another is not to be regarded as dishonest:
(a) if he appropriates the property in the belief that he has in law the right to deprive the other of it, on behalf of himself or of a third person; or
(b) if he appropriates the property in the belief that he would have the other’s consent if the other knew of the appropriation and the circumstances of it; or
(c) (except where the property came to him as trustee or personal representative) if he appropriates the property in the belief that the person to whom the property belongs cannot be discovered by taking reasonable steps.
s2(2). A person’s appropriation of property belonging to another may be dishonest notwithstanding that he is willing to pay for the property.
Baker (Dennis J. Baker, Glanville Williams Textbook of Criminal Law, (London: Sweet & Maxwell, 2012) at p. 1058 writes: "The traditional notion of theft involves an intent to deprive the owner permanently, not just to make a temporary use of his property. A person is not guilty of theft in “borrowing” a neighbour’s lawn-mower for the day while the neighbour is out, even if that is reckoned as dishonest. Is the law the same if a shop assistant “borrows” money from his employer’s till, intending to replace it when his ship comes in? Unlike the taker of the mower he intends to deprive his employer of those particular coins or notes permanently, even if he has every prospect of replacing them in a short time. So he can be guilty of theft."
- The s2(1)(a) claim of right is a difficult concept in that it represents a statutory exception to the fundamental public policy principle ignorantia juris non excusat and allows a limited mistake of law defence. According to R v Turner (No2)  2 All ER 441, a case in which a man was charged with the s1 Theft of his own car, the test was one of honest belief in a right, not a mere permission, to act in the particular way. In this, the test is subjective and a matter of fact for the jury to decide.
- If the owner or some person able to give a valid consent, actually consented to the taking, the property would not belong to another and no actus reus would exist. This provision applies to the situation in which either the consent is void ab initio or is subsequently voided. If the existence or effect of the vitiating factor is not recognised by the defendant, then he would not be dishonest. For example, if a contract was affected by a common or mutual mistake. But if the defendant is initially innocent, he may become dishonest is he later realises the mistake and decides to keep the property (i.e. an omission). Similarly, if has knowingly misrepresented a material fact and this has induced a consent that he knows or ought to know would not have been freely given, he will be dishonest.
- Defendants who are in a fiduciary relationship are expected to make even unreasonable efforts to identify where the relevant property has come from, but the ordinary defendant who finds property apparently abandoned on the street may not be dishonest if there are no serial numbers or marks that would help to identify the owner. Note that to be abandoned, the owner must have intended to give up all rights in the property and not to pass those rights to another. For example, material discarded in a rubbish bin is not abandoned. The owner intends another to come, empty the bin and dispose of the property without stealing it in the process. Hence, it will be theft to remove any property from a bin or legal disposal site.
- If the defendant knows that the owner will not sell the property, so takes the property in any event but leaves a realistic sum of money by way of payment, this will be a dishonest appropriation.
For the purposes of the deception offences, dishonesty is a separate element to be proved. The fact that a defendant knowingly deceives the owner into parting with possession of property does not, of itself, prove the dishonesty. This distinguishes between "obtaining by a dishonest deception" and "dishonestly obtains by a deception".
See also 
- The effect of anomie on academic dishonesty among university students. Albert Caruana, B. Ramaseshan, Michael T. Ewing Journal: International Journal of Educational Management Year: 2000 Volume: 14 Issue: 1 Page: 23 - 30
- Allen, Michael. Textbook on Criminal Law. Oxford University Press, Oxford. (2005) ISBN 0-19-927918-7.
- Criminal Law Revision Committee. 8th Report. Theft and Related Offences. Cmnd. 2977
- Griew "Dishonesty: The Objections to Feely and Ghosh"  CLR 341.
- Griew, Edward. Theft Acts 1968 & 1978, Sweet & Maxwell. ISBN 0-421-19960-1
- Halpin "The Test for Dishonesty"  Crim LR 283.
- Ormerod, David. Smith and Hogan Criminal Law, LexisNexis, London. (2005) ISBN 0-406-97730-5
- Smith, J. C. Law of Theft, LexisNexis: London. (1997) ISBN 0-406-89545-7