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Following the case of R v Hester, the demand remains in existence as a continuous demand until it has been withdrawn.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. These can be express or implied.

What is meant by menaces?

Menaces means that there must be some high degree of coercion to force an individual to undertake a particular course of action.

Do menaces have to be threats of physical violence?

Although menaces can include a threat of physical violence, other forms – such as a threat to expose a secret – can constitute blackmail for the purposes of TA 1968.

Does the individual who is making the demand have to be the same individual who will carry out the menaces?

There is no requirement to show that the individual who is making the demand is the same individual who is carrying out the menaces. Neither is it a requirement to show that the person making the demand is in a position to undertake the threatened action.

Unwarranted demand

A demand with menaces will be regarded as unwarranted unless the person making the demand believes both of the following:

  • That they had reasonable grounds for making the demand.
  • That the use of menaces is a proper means of reinforcing the demand.

How can it be shown the defendant believed the above two factors?

The test is subjective so when looking at the two factors above, it is the belief of the defendant which is important. Whether they are actually entitled to the money or property demanded is therefore not relevant.

With a view to make a gain or intent to cause a loss

Section 34 of TA 1968 defines gain and loss as including only gain and loss of money or other property.

Would demands of a sexual nature fall within the remit of the Theft Act?

Under s 34 of TA 1968, demands of a sexual nature would fall outside the remit of blackmail.

What is the maximum prison sentence for blackmail?

For the offence of blackmail under TA 1968, the maximum prison sentence is 14 years.

Article written by...
Lucy Trevelyan LLB
Lucy Trevelyan LLB

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Lucy graduated in law from the University of Greenwich, and is also an NCTJ trained journalist. A legal writer and editor with over 20 years' experience writing about the law.