(1)A person commits an offence if, in circumstances falling within subsection (2)—
(a)he does an act which harms, and is intended to harm, another person; or
(b)intending to cause another person to fear harm, he threatens to do an act which would harm that other person.
(2)The circumstances fall within this subsection if—
(a)the person doing or threatening to do the act does so knowing or believing that some person (whether or not the person harmed or threatened or the person against whom harm is threatened) has been a witness in relevant proceedings; and
(b)he does or threatens to do that act because of that knowledge or belief.
(3)If, in proceedings against a person for an offence under this section, it is proved that, within the relevant period—
(a)he did an act which harmed, and was intended to harm, another person, or
(b)intending to cause another person to fear harm, he threatened to do an act which would harm that other person,
and that he did the act, or (as the case may be) threatened to do the act, with the knowledge or belief required by paragraph (a) of subsection (2), he shall be presumed, unless the contrary is shown, to have done the act, or (as the case may be) threatened to do the act, because of that knowledge or belief.
(4)For the purposes of this section it is immaterial—
(a)whether or not the act that is done or threatened, or the threat that is made, is or would be done or is made in the presence of the person who is or would be harmed or of the person who is threatened;
(b)whether or not the motive mentioned in subsection (2)(b) is the predominating motive for the act or threat; and
(c)whether the harm that is done or threatened is physical or financial or is harm to a person or to his property.
(5)A person guilty of an offence under this section shall be liable—
(a)on conviction on indictment, to imprisonment for a term not exceeding five years or to a fine, or to both;
(b)on summary conviction, to imprisonment for a term not exceeding six months or to a fine not exceeding the statutory maximum, or to both.
(6)In this section “the relevant period”, in relation to an act done, or threat made, with the knowledge or belief that a person has been a witness in any relevant proceedings, means the period that begins with the commencement of those proceedings and ends one year after they are finally concluded.
(7)References in this section to a witness, in relation to any proceedings, include references to a person who has provided any information or any document or other thing which was or might have been used as evidence in those proceedings or which (whether or not it was admissible as evidence in those proceedings)—
(a)tended to confirm or might have tended to confirm any evidence which was or could have been given in those proceedings;
(b)was or might have been referred to in evidence given in those proceedings by another witness; or
(c)was or might have been used as the basis for any cross examination in the course of those proceedings.
(8)This section is in addition to, and not in derogation of, any offence subsisting at common law.