The bell has sounded ending one more round in what is shaping up to be a long-running bout between the county's highest court and the Harper government.

The latest skirmish erupted Friday when the Supreme Court of Canada once again softened the Conservative government's tough-on-crime agenda.

In a unanimous 7-0 ruling, the high court affirmed that offenders can receive extra credit for time spent in custody before they are sentenced.

The Conservatives' Truth in Sentencing Act had reduced the discretion of judges to give an offender credit for their time served in pre-trial custody.

Justice Minister Peter MacKay fired back with a terse statement that affirmed the government's long-held belief that violent criminals should face hard time for their crimes.

The Supreme Court was ruling on three cases that related to the 2009 law that toughened the sentencing provisions for repeat and violent offenders. The law removed the long-held provision of giving an offender credit for double the time already served when they are being sentenced.

The Tories removed the provision, but the law still allowed for a credit of 1.5 times in exceptional circumstances, though the specifics were never defined.

The Supreme Court filled that void Friday and declared that pre-trial custody constitutes a circumstance that warrants the full 1.5 credit.

"Had Parliament intended to alter the well-established rule that enhanced credit compensates for the loss of eligibility for early release, it would have done so expressly," said the ruling, written by Justice Andromache Karakatsanis.

"I conclude that loss of access to parole and early release constitutes a 'circumstance' capable of justifying enhanced credit."

Provide guidance

Friday's rulings were not constitutional cases, and they do not strike down any laws. But they will serve as legal precedents that will provide guidance for judges when they sentence offenders.

They also represent the latest in a series of court rebukes of the Conservative government's law-and-order agenda.

MacKay said his office would review the "implications" of the decision, but was quick to say that the court had not in fact dampened the time-served rollback of its 2009 law.

"These limits remain in effect," MacKay said in a statement that invoked the government's usual tough-on-crime line.

"Canadians expect violent criminals to serve sentences which reflect the severity of their crimes. They became increasingly concerned that convicted criminals would receive two for one and sometimes three for one credit for time served off their sentence," the minister said.

"This is why our government acted with legislation, supported by provincial and territorial attorneys general, to limit the credit to one for one and allowing up to 1.5 for one where circumstances justify doing so."

'Slap in the face'

The federal New Democrats characterized Friday's rulings as a clear rebuke of the Conservative government's crime agenda.

"It's a slap in the face for the government," said the NDP's parliamentary reform critic Craig Scott.

"If the government had wanted to achieve the result they argued in the court, they should have written the legislation differently. And so it's another slap down of the court for the government saying, 'you know, if you're going to have this kind of agenda, do your homework'."

Lawyers for the Canadian Civil Liberties Association, which was granted intervener status in the case, said the ruling restores the discretion that judges need at sentencing.

"The court has recognized that without clear language from Parliament to limit a long-standing approach to sentencing, offenders should not be punished more severely solely because they were not released on bail," the group said in a statement.

The Supreme Court's rulings on Friday included one involving a young man convicted of manslaughter in the shaking death of his infant daughter, and who was given the 1.5 credit.

In May 2011, Sean Summers, then 20, had his eight-year sentence reduced to six years and eight months to credit him one and a half times for his time already served after he pleaded guilty and showed remorse for the crime.

"A rule that results in longer sentences for offenders who do not obtain bail, compared to otherwise identical offenders does not result in 'similar ... sentences imposed on similar offenders for similar offences committed in similar circumstances'," said the ruling.

The Harper government and the Supreme Court will do battle again.

On Thursday, the Supreme Court also agreed to hear two more cases on whether the government's changes to mandatory-minimum sentences for unlawful gun possession are constitutional.

One month ago, the high court struck down retroactive changes to parole eligibility that the Conservatives had enacted. In that case, it ruled that the Abolition of Early Parole Act was unconstitutional because it imposed new punishment on people who had already been tried and sentenced.

The lower courts have also pushed back against the Tories' crime agenda, as judges in at least three provinces have taken steps against a new mandatory victim surcharge, saying it places an unfair burden on those who don't have the means to pay. In those cases, the judges have either refused to order criminals to pay the mandatory surcharge or attempted to render it impossible for authorities to collect the fee.

The Supreme Court also dealt the Harper government another major setback last month when it rejected its appointment of Justice Marc Nadon, ruling that the semi-retired Federal Court of Appeal judge did not have the proper qualifications laid out in the Supreme Court Act for a Quebec nominee.

Mobile users, read the rulings here (PDFs):

R v Carvery (pre-trial credit)

R v Summers (pre-trial credit)

R v Clarke (retroactivity)