Criminal Law (Ireland) Act, 1828

On conviction of felony of a person under sentence for a former crime, the court may pass a second sentence, to commence after the expiration of the first.

20. Whenever sentence shall be passed for felony on a person already imprisoned under sentence for another crime, it shall be lawful for the court to award imprisonment for the subsequent offence, to commence at the expiration of the imprisonment to which such person shall have been previously sentenced; and where such person shall be already under sentence, either of imprisonment or of transportation, the court, if empowered to pass sentence of transportation, may award such sentence for the subsequent offence, to commence at the expiration of the imprisonment or transportation to which such person shall have been previously sentenced, although the aggregate term of imprisonment or transportation respectively may exceed the term for which either of those punishments could be otherwise awarded.