The government's plan to introduce identity cards poses a "fundamental" threat to civil liberties, Liberal Democrats have heard.
Delegates at the party's annual conference in Blackpool also criticised proposals to detain terror suspects for up to 90 days.
Alex Wilcock, from London, said ID cards would "destroy our privacy and the most private areas of our lives".
Ministers say they are necessary to combat the threat of terrorism.
'Reinforce the law'
However, Northern Ireland spokesman Lembit Opik said: "Terrorism isn't about identity; it's about motivation."
Lib Dem delegates voted to oppose the government's Prevention of Terrorism Bill, which makes "glorifying" terrorism an offence and extends the maximum period of detention without charge to 90 days.
MP Alistair Carmichael said: "If we cannot defend liberties as fundamental as these, then there won't be any point to being in parliament at all."
Joanna Shaw, from Camberwell and Peckham, described Tony Blair and Home Secretary Charles Clarke as "the hideous spectre of a pair of jack-booted nannies standing before us".
The conference voted unanimously to give "full respect to human rights and the rule of law".