Three Dublin men are seeking their release from prison following a loophole that temporarily legalised drugs like ecstasy, crystal meth and ketamine last month.

The men were convicted with drugs offences under the 1977 Misuse of Drugs Act which was struck down as unconstitutional by the Court of Appeal.

Anthony Murphy of Galtymore Road, Drimnagh was jailed for five years for having over €500,000 worth of synthetic cannabis.

Keith Willis from Rossmore Avenue, Ballyfermot was caught with 5,000 ecstasy tablets.

While Joseph Carberry of Lonsdale Terrace, Ballymun was given an 11 year sentence for possessing pentedrone - described as a cocaine-like synthetic drug.

All three men pleaded guilty, but are now challenging the lawfulness of their detention following last month's Court of Appeal ruling striking down the 1977 Misuse of Drugs Act.

Their lawyers say they are serving time for offences that did not exist at the time of their convictions.

The loophole meant drugs like ecstasy and crystal meth were for a brief period legal, before the Oireachtas plugged the gap with emergency legislation.

High Court President Nicholas Kearns will give a ruling later this month.