The Criminal Law Act 1977 (c. 45) is an act of the Parliament of the United Kingdom. Most of it only applies to England and Wales. It creates the offence of conspiracy in English law. It also created offences concerned with criminal trespass in premises, made changes to sentencing, and created an offence of falsely reporting the existence of a bomb.

This Part implemented recommendations contained in the Report on Conspiracy and Criminal Law Reform (Law Com 76) by the Law Commission.

Section 6 creates an offence of using or threatening unauthorised violence for the purpose of securing entry into any premises, while there is known to be a person inside opposing entry. Violence is taken to include violence to property, as well as to people.

This section has been widely used by squatters in England and Wales, as it makes it a crime in most circumstances for the landlord to force entry, as long as the squatters are physically present and express opposition to the landlord's entry. "Squatters' rights" do not apply when the property appears to be occupied (e.g. there are signs of current use, furniture, etc.).

Section 6 is referred to in printed legal warnings, which are commonly displayed near the entrances to squatted buildings. Squatters are not protected by the Protection from Eviction Act 1977, which makes it a crime to evict tenants without following the legal process.

Reasonable force used by a bailiff executing a possession order would not be considered unauthorised violence, so landlords can still legally regain possession through the courts.

Laws regarding squatting residential properties were revised in the Legal Aid, Sentencing and Punishment of Offenders Act 2012.

The purpose of this offence is to fill the lacuna that might otherwise have been left in the law by the abolition of the common law offence of conspiracy to trespass by section 5(1) of the Act.