Tim Farron has told ITV News Theresa May's pledge to change human rights legislation in the wake of recent terror attacks would be playing into the hands of terrorists.
Theresa May announced on Tuesday she would change human rights laws if they were stopping authorities tackling terrorism.
Asked about the prime ministers proposal, the Liberal Democrat leader said: "When all is said and done, changing the law is not what keeps us safe. Investing in our police and in our intelligence and security services - that Theresa May has cut - that is what would keep us safe.
"The danger is on the eve of an election, politicians will sometimes try and do something that looks good but we all know doesn't do us any good.
"And the minute we start throwing away our rights and our freedoms as a society is the moment we start to let the terrorists win."
Liberal Democrat leader Tim Farron served up a Brexit-themed breakfast at a German cafe in Solihull on the final day of campaigning.
Mr Farron handed out the sausage and sauerkraut to supporters, but refused requests from reporters to eat it on camera as he wanted to try and avoid "the Miliband moment".
He was joined by Ade Adeyemo, the local Lib Dem candidate for Solihull.
The Lib Dems have pledged to have a second EU referendum over the final Brexit deal should they win on 8 June.
Liberal Democrat Sir Vince Cable has denied the Liberal Democrats' stance on a second referendum over the EU exit deal goes against the "will of the people".
Speaking to Good Morning Britain, Sir Vince said: "The whole point of the second referendum is not about second guessing what the public have already voted for - or be it narrowly.
"It's not disregarding the will of the people, it's asking a different question in different circumstances."
He told presenters Piers Morgan and Susanna Reid he was "confident" the Lib Dems would do better in this general election after the party's poor performance in 2015.
He also admitted the naughtiest thing he had ever done was shoot at neighbours' windows with an air rifle when he was a child.
Liberal Democrat Nick Clegg has accused Labour and the Conservatives of following a "pact of silence" over Brexit that leaves voters short changed.
The former Lib Dem leader claimed that the two main parties had "colluded to evade all meaningful scrutiny of their Brexit plans - if indeed they have any."
Both now have "more or less identical" stances: pledging to pull out of the common market, end freedom of movement and deny the people a vote on the final exit deal, he said.
The truth is there has been a pact of silence on Brexit between Theresa May and Jeremy Corbyn.
It is one of the most cynical acts of political collusion between the two larger parties in a generation.
From gay marriage to cannabis and what keeps him awake at night, here's what Mr Farron had to say during an ITV News Facebook Live.Read the full story ›
Ahead of the election, the Liberal Democrat leader will answer questions submitted by the online audience, as part of ITV News Leaders Live.Read the full story ›
Tim Farron takes part in a Facebook Live Q&A session with the voting public as part of ITV News Leaders Live.Read the full story ›
Brexit on Theresa May's terms could see the UK lose access to a database of information on terrorists and criminals, the Lib Dems have said.Read the full story ›
The Lib Dems have a launched a bizarre election poster campaign - featuring Nigel Farage's face superimposed onto Theresa May's body.Read the full story ›
Liberal Democrat leader Tim Farron has accused Theresa May of taking the election result "for granted" by believing she can win despite not appearing in Thursday's televised leaders' debate.
Speaking ahead of the event, he said he was looking forward to putting forward the Lib Dems' "strong alternative" to the "extreme" Brexit supported by some of the other parties involved.
I think the disappointment for everybody in this country, no matter how you're planning to vote, is the Prime Minister is taking the electorate for granted, not even choosing to come along to the debates in the first place.
And that tells you all you need to know about what she thinks about you, and what she thinks about her chances of winning anyway.
It's why it's important that a strong alternative to the Conservatives, with a different path about not going down the extreme version of Brexit that Theresa May, Jeremy Corbyn and Ukip all voted for - it's so important that that alternative is put forward tonight, and I will do my best to do that.
ITV has invited all party leaders to attend and the invitation remains open until the debate begins.