Trade Union and Labour Relations (Consolidation) Act 1992.
Section 241 – Intimidation or annoyance by violence or otherwise.
This law is rarely used against protesters, but has been heard of in cases against people protesting the building or expansion of roads and those protesting the badger cull. Activists conducting FITwatch activities (www.fitwatch.org.uk) were once arrested under this act, but the charges were later changed to obstruction of police officers (see s89 Police Act 1996 for more information on this offence).
(1)A person commits an offence who, with a view to compelling another person to abstain from doing or to do any act which that person has a legal right to do or abstain from doing, wrongfully and without legal authority—
(a)uses violence to or intimidates that person or his spouse or civil partner or children, or injures his property,
(b)persistently follows that person about from place to place,
(c)hides any tools, clothes or other property owned or used by that person, or deprives him of or hinders him in the use thereof,
(d)watches or besets the house or other place where that person resides, works, carries on business or happens to be, or the approach to any such house or place, or
(e)follows that person with two or more other persons in a disorderly manner in or through any street or road.
(2) A person guilty of an offence under this section is liable on summary conviction to imprisonment for a term not exceeding six months or a fine not exceeding level 5 on the standard scale, or both.