The word 'conscience' means the inner sense of what is right or wrong in one's conduct or motives. Behaviour is described as 'unconscionable' when it does not conform to what the inner sense of conscience prescribes. In modern Australian law, unconscionable behaviour is not tolerated. Such behaviour may make a legal transaction voidable or, in some circumstances, unenforceable.
Even when parties are dealing at arm's length, rather than on the basis of trust, it is not permissible for either party to take improper advantage of another's known weakness, or to do anything which, in good conscience, ought not to be done.