The federal government introduced a bill on Tuesday that would make it easier to designate criminals as dangerous offenders.

The bill, which would amend the Criminal Code, calls for tougher sentences and stricter conditions on repeat offenders who have been convicted of a third sexual or violent offence.

Under the bill, the onus would be put on convicted criminals to prove they should not be declared dangerous offenders, otherwise they would be designated as dangerous and be given an indeterminate jail sentence, with no eligibility for parole for seven years.

Currently, the Crown must show at a hearing why an individual should be declared a dangerous offender.

Justice Minister Vic Toews introduced the bill in the House of Commons Tuesday morning.

"We need this bill in order to ensure that Canadians are protected against dangerous offenders," Toews said after the bill was tabled.

"What it does, in effect, after the third conviction of a very serious offence, it then becomes incumbent on the convicted person to demonstrate to the court why he or she should not be declared a dangerous offender.

"It absolutely will act as a deterrent, it is not unconstitutional and we have considered it very carefully."

More restrictions

The bill would also increase the maximum duration of peace bonds from 12 to 24 months, allowing additional restrictions and conditions to be placed on released criminals.

Susan Barnes, the federal Liberal justice critic, told CBC News on Tuesday she plans to look at the bill closely, section by section, to determine whether it would withstand a challenge under the Canadian Charter of Rights and Freedoms.

"We are going to have to look at the details of this piece of legislation inside our caucus. This is a piece of legislation that could have an unintended consequence in terms of backlogging the whole justice system," she said.

NDP justice critic Joe Comartin was skeptical of the proposed legislation, calling the bill "a bit of an overkill" and saying he has serious doubts that it could stand up to a constitutional challenge.

"This is political posturing," Comartin said.

Praise and criticism

He said he thinks it has little chance of passing the Commons before next spring, when another federal election is widely expected.

The bill has received praise from victims' rights advocates, but defence lawyers have said it goes too far and could undergo a constitutional challenge if it becomes law.

"This will be a controversial piece of legislation in some quarters, but it will be welcomed in others that voted for a Conservative government," said Keith Boag, CBC Television's Ottawa bureau chief.

"It is foreign to our justice system in a way," he said.

The Harper government has introduced a number of crime bills recently, including legislation that would impose mandatory minimum sentences for gun crimes and curtail the use of house arrest as an alternative to jail time for certain offences.