Human rights rulings make the UK a 'safe haven' for suspected foreign terrorists, the independent reviewer of anti-terror laws warned today.
Lord Carlile said the dismissal of the Government's argument that the risk of ill treatment on deportation for foreign nationals had to be balanced against the threat they posed when they are allowed to stay in Britain caused problems.
'The effect is to make the UK a safe haven for some individuals whose determination is to damage the UK and its citizens - hardly a satisfactory situation save for the purist,' he said.
In his annual review of counter-terror legislation published today, Lord Carlile backed the Government's attempts to deport suspected foreign terrorists with assurances over their treatment once returned home.
But he warned that it was a 'time-consuming process, requiring assurances that are public, credible and reliable'.
Even once agreed, 'there is no guarantee that the courts will accept them, given the relatively low legal threshold required for an individual to avoid deportation', he said.
The Government has argued that, where a person seeks to resist removal on the grounds of the risk of ill-treatment in their home country, this may be balanced against the threat they pose to national security if they remain.
It also argued that, if the person poses a risk to national security, this should affect the standard to which he must establish the risk of ill-treatment.
But both arguments were rejected by the European Court of Human Rights, Lord Carlile said.
'This leaves the UK reliant on DWA (deportation with assurances) arrangements.'
Arrangements currently exist with Algeria, Jordan, Ethiopia, Libya and Lebanon, although the latter may need to be renegotiated 'in the light of political developments there', he said.
Home Secretary Theresa May last week outlined plans for a stronger effort to deport foreign nationals involved in terrorist activity.
On control orders, Lord Carlile said the proposed replacement - terrorism prevention and investigation measures, or Tpims - 'shares several characteristics with control orders (and would provide commensurate protection)'.
'There is an acceptable balance of risk against other considerations,' he said. 'It should be seen as adopting a new approach to public protection against terrorism.'
Lord Carlile went on: 'In stark terms, the potential cost of losing control orders now is that the UK would be more vulnerable to a successful terrorist attack.'
But he added that, in future, at least two members of the Opposition should undergo developed vetting and should be given 'detailed knowledge of the evidence base for control orders, generally and in relation to individuals'.
'The purpose of this would be that, whilst respecting confidentiality and national security, they should be able to give informed advice to their shadow colleagues on the merits of the legislation,' he said.
He added that control orders, or their replacement, should only be used when prosecution was not possible and added that it was 'unlikely' that the use of intercept evidence in court would have led to the prosecution of any controlees since control orders were introduced in 2005