Two cases against men charged with dissident republican activity have been withdrawn because of concerns over low copy number DNA testing.
The Omagh verdict cast doubt on low copy number DNA testing
The controversial technique was criticised during the Omagh bomb trial.
An attempted murder charge against John Brady, 38, from Strabane was dropped, as were incendiary charges against Barrie Devine, 19, also from Strabane.
The decisions could place a question mark over the use of the technique in a number of other cases.
Mr Brady has been in jail for four years, charged with the attempted murder of a part-time member of the Royal Irish Regiment in Sion Mills in 2002.
He was expected to go trial on Monday, but the Public Prosecution Service informed his defence lawyers the case has been withdrawn.
The decision was taken after a review of all cases involving low copy number DNA evidence.
The technique is highly sensitive and can be used to test DNA samples 1,000 times smaller than a grain of salt.
The PSNI suspended the use of the technique after it was strongly criticised by the judge in the Omagh bomb trial.
The charges against Mr Devine were also dropped for the same reason.
He was expected to go on trial next month charged with making and possessing an incendiary device.
A number of other cases which rely upon the technique are expected to come before the courts in the near future.
Defence lawyers have called for those cases to be withdrawn.