Is it necessary or practical to make known to a person arrested the reason why they are being arrested?

While there are occasions when the circumstances are such that it may not be necessary or practical to make known to a person arrested the reason why he is seized, such cases are the exception to the general rule as it was enunciated by Lord du Parcq in Christie v. Leachinsky, [1947] A.C. 573, [1947] 1 All E.R. 567 at 578: “The principles established by the authorities are agreeable to common sense, and follow from the governing rule of the common law that a man is entitled to his liberty, and may, if necessary, defend his own freedom by force. If another person has a lawful reason for seeking to deprive him of that liberty, that person must as a general rule tell him what the reason is, for, unless he is told, he cannot be expected to submit to arrest or be blamed for resistance.”