The Interception of Communications Act 1985 (1985 c. 56) was an Act of Parliament in the United Kingdom. It came into operation as of 10 April 1986. The Act created the offence of unlawfully intercepting communications sent by post or by a "public telecommunications system"; those guilty were liable, on conviction, to a fine or up to two years imprisonment. It provided for a system of warrants to permit legal interception, and laid down cases where interception could be done lawfully, stating that having reasonable grounds to believe that the other party consented to interception was a defence.