How to prove blackmail

What is blackmail under UK law?

The criminal offence of blackmail under the s 21 of the Theft Act 1968 (TA 1968) is the act of making an unwarranted demand with menaces with a view to making a gain or causing a loss.

What elements need to be established to prove blackmail?

To prove blackmail it must be shown the defendant did the following things:

  • made a demand;
  • with menaces;
  • that the demand was unwarranted; and
  • that the defendant has a view to make a gain for himself or another or have intent to cause a loss to another.


Does the demand have to be an express demand?

There is no requirement under TA 1968 to show that a demand had been made expressly. If a demand is implied, this may be enough to prove blackmail.

What is the case if a demand has been made by post?

Where a demand has been made by post, the demand will be deemed to have been made the moment it is posted. This means the demand will have been made before the individual upon whom the demand is placed was even aware of it occurring. There is, therefore, no need for the victim to be aware of the demand for it to arise.

Can this be extended to other forms of communication such as email?

This is not limited to just postal communication. Forms of communication such as email or text message will also be included. Since there is no need for the victim to be aware of the demand for it to be made, it could take the form of an unread email, a text message or an answer machine message which has not yet been listened to.

Is it possible to withdraw the demand?

Following the case of R v Hester, the demand remains in existence as a continuous demand until it has been withdrawn.


For liability for blackmail to arise under TA 1968, the demand must be accompanied by menaces.

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For more information on:

  • Unwarranted demand
  • With a view to make a gain or intent to cause a loss
  • What is the maximum prison sentence for blackmail?