Police bugged the headquarters of an animal rights group accused of using threats against suppliers of an animal testing laboratory, a court has heard.
Five defendants, from Hampshire, Newcastle and London, are accused of blackmailing firms with links to Huntingdon Life Sciences in Cambridge.
The five were allegedly part of Stop Huntingdon Animal Cruelty, which had its headquarters near Hook, Hampshire.
Winchester Crown Court heard audio from a meeting in 2007 had been recorded.
Heather Nicholson, 41, of Eversley, Hampshire, Trevor Holmes, 51, of Newcastle; Gerrah Selby, 20, of Chiswick, London; Daniel Wadham, 21, of Bromley, south London and Gavin Medd-Hall, 45, of Croydon, south London, are accused of being closely involved in a campaign from 2001 until 2007, which targeted companies in Britain and Europe.
All five deny conspiracy to blackmail.