The UK has become a "safe haven" for foreign suspects, the outgoing terror laws watchdog has said.
In his last report, Lord Carlile said rulings from the European Court of Human Rights meant it was difficult to remove dangerous people.
He said the UK was relying on foreign states' assurances about the treatment of suspects that judges may not accept.
He also said the political debate over replacing control orders had been "poorly informed" at times.
In his sixth annual report Lord Carlile, a QC and Liberal Democrat peer, said that the UK had failed to persuade the European Court that the risk of ill-treatment faced by a detainee in his home country had to be balanced with the threat posed to the UK's national security.
The UK had deals over the treatement of deportees with Algeria, Jordan, Ethiopia and Libya - but Lord Carlile said the legal chances of avoiding removal remained high.
"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," he said.
"I support the proposals in the Counter-Terrorism Review that the Government should pursue deportation arrangements with more countries. I support very strongly efforts to pursue verifiable assurances for named individuals, in relation to countries with which there is no generic agreement.
"In addition, I suggest that my successor should be commissioned to provide an annual independent report on deportations in terrorism cases, and the monitoring/verification of their situation after deportation."
Lord Carlile said that control orders remained the best means of monitoring suspects who could be neither deported nor tried for an offence.
But he called for a formal security services-approved system of briefing opposition figures, which could take some of the "political steam" out of the "poorly informed debate" over the proposed replacement for the current system.
"The manifestos of the [coalition] political parties then in opposition were written without detailed knowledge of the evidence base for control orders, generally and in relation to individuals," he said.
"In my view this is regrettable, and should be remedied in the present system and any legislative replacement.
"I recommend that one or two senior spokespersons for at least the official Opposition should be… vetted: 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."
The coalition has pledged to replace control orders with a new regime called Terrorism Prevention and Investigation Measures.
http://www.bbc.co.uk/news/uk-politics-12356563
