OTTAWA — One expert after another is warning the federal government that its massive crime bill will do more harm than good, costing taxpayers dearly for a punitive system that will only serve to make the streets more dangerous.

But Conservative MPs are questioning the credibility of those experts, suggesting they are advocating for criminals or are too detached from the real world to offer solid advice.

"We believe the substance of this legislation both to be self-defeating and counterproductive, if the goal is to enhance public safety," Eric Gottardi, vice-chair of the Canadian Bar Association's national criminal justice section, said Tuesday.

"It represents a profound shift in orientation from a system that emphasizes public safety ... rehabilitation and reintegration to one that puts vengeance first."

The omnibus bill merges nine previous pieces of legislation, and adds new elements, tying them into a massive package that critics say is an "incoherent" attempt to crack down on dangerous criminals.

The package fulfills a key Conservative election promise to bring forward failed or languishing anti-crime legislation from previous parliaments within 100 days of the new government.

Tuesday was the first full session of hearings from witnesses, establishing an uncomfortable tone.

The measures aim to toughen penalties for drug traffickers, child-sex crimes and violent young offenders. The bill would also make pardons more difficult to obtain. And it would give victims of crime more rights to have their voices heard in the parole system.

Indeed, victims' groups spoke out in favour of the bill, dubbed C-10, saying they will appreciate having more say during parole hearings, and receiving more information about the status of offenders.

Sharon Rosenfeldt, president of Victims of Violence, says she hears critics' concerns about the costs of keeping more criminals in prisons longer, but she believes the price is worth paying to keep dangerous people off the streets.

"This is a necessary cost for the protection of society," she told the justice committee.

The cost of incarceration pales in comparison to the toll crimes take on their victims, she said.

Her son Daryn Johnsrude was murdered by serial-killer Clifford Olson in 1981. He would not have died if C-10 had been in place back then, she argued.

The emotional pleas and personal attacks have been a hallmark of debate on the many crime bills brought forward by the Conservatives over recent years.

On Tuesday, the head of the John Howard Society was labelled an "advocate for criminals" after she argued that the bill would provoke Charter challenges.

Catherine Latimer said C-10 removes some of the rights of young offenders, and will also lead to deteriorating conditions in prisons that are already overcrowded, while paying little attention to rehabilitation and reintegration.

Conservative MPs also questioned the credentials of University of Toronto criminologist Anthony Doob and University of Ottawa criminologist Eugene Oscapella, suggesting they were too far removed from real life to offer relevant advice.

The Conservatives say their bill is effective and affordable, at a cost of $78.5 million over five years -- a figure that does not include costs to provincial governments who run the majority of jails.

They also pointed to testimony from Don Head, commissioner of the Correctional Service of Canada, who said prisons would adjust and expand to deal with a populations. And they pointed to sections of the bill that would allow for drug offenders to seek treatment.

But critics argue that the cumulative effect of so many crime bills rolled into one package is making it difficult to figure out the good from the bad.

"This is a cruel and dishonest joke on the part of Parliament," said Doob. "A law purposely made incoherent does not deserve respect."