The Supreme Court of Canada has agreed to hear a pair of cases involving elements of the Harper government's "tough-on-crime" agenda.
The first case involves three prisoners sentenced before the passage of a 2011 law that toughened parole conditions.
The prisoners argued they should have been treated under the old law, which allowed early parole after serving one-sixth of a sentence.
They won in lower courts, but the Supreme Court agreed to hear the attorney general's appeal.
The second case deals with credit for pre-trial detention.
A lower court judge credited the offender with 1.5 days for each day in detention before sentencing, which the federal government appealed.
The Conservatives have sought to crack down on early parole for non-violent offenders and tougher pre-trial custody and sentencing provisions for repeat and violent youth offenders.
As is its usual practice, the high court did not release reasons for its decision.