MPs say a review of anti-terror laws should be an urgent priority
All counter-terrorism laws passed since 11 September 2001 should be reviewed to see if they are still necessary, says a committee of MPs and peers.
It questioned whether ministers could legitimately argue, nine years on, that a "public emergency threatening the life of the nation" remained.
And it said the government's "narrow" definition of what amounted to complicity in torture was "worrying".
The government says the threat from terrorism remains "real and serious".
In its report, Parliament's joint committee on human rights said it was pleased to see that ministers said a commitment to human rights "underpinned" counter-terrorism work.
But it said "all too often" this were "squeezed out by the imperatives of national security and public safety".
It said the government should drop entirely its plan to extend the period terrorism suspects can be held without charge from 28 to 42 days.
The plan was shelved in the face of opposition in the House of Lords but remains as a draft bill, to be enacted if needed. The committee said the draft bill was "alarmingly broad".
MI6 chief Sir John Scarlett denied security services were complicit in torture
The need for the current 28-day limit, extended from 14 days in 2005, should be revisited and bail should be considered "in principle" for some terrorist suspects, the committee said.
It complained that the intelligence agencies' insistence on control over the examination and transcription of intercept evidence - like phone taps - amounted to a "de facto veto" of efforts to see it used as evidence in court.
The committee asked whether it was realistic to continue to say the same state of emergency as in September 2001 still remained.
The government then used the "public emergency test" to derogate from the European Convention on Human Rights, so it could detain foreign terrorist suspects without trial.
That was ruled illegal in 2005, but the committee said the government had "never relinquished its assertion that there is a public emergency threatening the life of the nation" - something which had a "deleterious effect on public debate" about anti-terror laws.
The committee pointed out that the threat level had fluctuated between "critical" and "substantial", according to the assessment of the Joint Terrorism Analysis Centre (JTAC). The government argued that the JTAC assessment and the "public emergency test" were independent of each other - the committee disagreed.
It added: "In our view it devalues the idea of a 'public emergency' to declare it in 2001, and then to continue to assert it more than eight years later."
The committee has already called for a full inquiry into claims UK security services were complicit in the torture of terrorism suspects - a claim denied by the head of MI6.
The government denies any complicity in torture, saying it "unreservedly condemns" it and does not "participate in, solicit, encourage of condone torture".
But the committee said ministers' definition of "complicity" was "very much narrower" than that of the committee.
The government said its position was "that the receipt of intelligence should not occur where it is known or believed that receipt would amount to encouragement to the intelligence services of other states to commit torture".
The committee said that was a "significant and worrying change in definition".
The threat to the UK from terrorism remains real and serious and we are committed to doing all we can to protect our nation's security
The wide-ranging report also says the independent reviewer of terrorism laws - currently Lord Carlisle - should be appointed by, and report directly to Parliament and criticises the head of MI5, Jonathan Evans, for choosing not to appear before the committee in public.
The committee's chairman, the Labour MP Andrew Dismore, said: "There is no question that we face a serious threat from terrorism, or that we need legislation to counter that threat.
"The question is, are the counter-terror measures we have in place justifiable, on an ongoing basis, in light of the most up-to-date information we have."
He said a "thoroughgoing, evidence-based review" of counter-terrorism laws passed since 2001 should be "an urgent priority for the next Parliament".
A Home Office spokeswoman said a full response to the report would be released in due course.
But she added: "We are pleased that the committee recognises our commitment to human rights, which are at the heart of our counter-terrorism legislation.
"The threat to the UK from terrorism remains real and serious and we are committed to doing all we can to protect our nation's security while protecting individual liberties using the proper safeguards."
Shadow Home Secretary Chris Grayling said all counter-terrorism laws passed since 2001 should be reviewed as a matter of urgency.
"The committee is right to question whether all of the legislation introduced since 2001 is proving effective or necessary," he said.
"But even more important is the need to stop the use of terror laws for other purposes, like routine stop and search and local authorities' surveillance of recycling habits."