Immanuel Kant was a German philosopher who wrote the book 'The Groundwork of the Metaphysics of Morals'. Within this theory he stresses the importance of duty and duty based ethics. At the heart of Kantian Ethics is the 'Categorical Imperative'; which can be followed by any rational person, they are based on an 'if'-they are moral ought's. In response to the question, Kant believed that under any circumstances - lying is always wrong regardless of its consequences. For many people in today's society it is hard not to lie; our moral duties are tested especially in difficult situations where lying could be the best procedure to create a satisfying consequence. But, for Kant, the law "remains in full force, because it commands categorically." (G,438-39/57) 1.
Kant's theory outlines two imperatives which are Hypothetical and Categorical. The Hypothetical Imperatives are based on an 'if'. We can reject the command as long as we are willing to reject the 'if'. The Categorical Imperative would be followed by any rational person; this is the main body of Kant's Moral Law theory. If we are to be virtuous, we must do our duty and ignore our inclinations. Being a moral person means not doing what comes naturally and usually involves an internal struggle against our wicked desires e.g. lying. By using reason we can then discover what our duty is-obeying a set of compulsory rules or categorical imperatives. Since the categorical imperatives are not based on an 'if' it does not depend on a particular end and Kant maintains that they would be followed by any rational human being. Our moral duties are categorical and should be followed for duty's sake only; they are duties and not for any other reason.
As previously stated, Kant would reject the notion to lie in all situations. He arrived at a number of different formulations of what he terms the 'Categorical Imperative' on which all moral commands are based.