A new study has revealed that four out of five people arrested using anti-terror legislation in Northern Ireland last year were not charged with an offence.
The security forces are on high alert for more attacks by violent dissident republicans, with the threat posed being described as severe.
David Anderson QC, who reviewed the figures, said they represented a ten-year low in the proportion of prosecutions to arrests.
Mr Anderson said that 32 or 19% of the 168 people arrested under the Terrorism Act in 2013/14 were charged using the legislation.
Despite this, last year saw a ten-year low in the proportion of prosecutions to arrests, an independent expert who scrutinises the law for ministers said.
One Belfast lawyer claimed the figures showed police had acted on a "spurious" basis.
However, the PSNI said charges may be brought using other firearms or explosives legislation not covered in the Terrorism Act 2000 figures.
Police have launched a series of high profile raids recently and believe they disrupted a meeting of suspected dissident republicans who were planning further attacks during an operation in Newry, Co Down, which had been set up by secret recordings made by MI5.
