Just before their summer break, MPs have passed a bill that would prevent schoolgirl killer Karla Homolka from seeking a pardon.

The lawyer for two families whose daughters were killed by Homolka and Paul Bernardo says the parliamentary deal to prevent Homolka from receiving a criminal pardon is a commendable achievement.

Lawyer Tim Danson says federal politicians should be applauded for their agreement, which will spare the victims' families from seeing the convicted killer get a parole she does not deserve.

"Certainly, we have to applaud the politicians -- that doesn't happen very often -- that they did act, reached a consensus so that she cannot apply for a pardon in a few weeks," Danson told CTV's Canada AM during an interview in Toronto on Thursday morning.

The bill must still be passed by the Senate, which is not adjourning right away.

Homolka served a 12-year sentence for her part in the notorious murders of Leslie Mahaffy and Kristen French, two Ontario teens who were abducted, sexually assaulted and killed.

The deal worked out in Parliament will see new legislation passed in the House of Commons Thursday that will extend the time period that a person convicted of a serious personal injury offence -- including manslaughter, violent assault and sexual assault -- has to wait before applying for a pardon.

Additionally, the National Parole Board will be expected to deny a pardon if it would severely damage the reputation of the justice system.

For Homolka, this second part of the legislation could effectively bar her from ever being pardoned for her crimes.

"One of the criteria for the National Parole Board is that you can't give a pardon that could bring the administration of justice into disrepute," said Danson.

"So, I think from a practical point of view, she will never get a pardon. But to be clear, she will be able to apply."

Danson said Homolka will still be able to apply for a pardon because she was convicted of manslaughter and not any sexual offences, despite the nature of the murders she was involved in.

Without the deal made in Parliament, Homolka would have been eligible to apply for a pardon next month.

Despite its benefits, Danson said the timing of the deal is especially hard on the Mahaffy family, whose daughter was killed 19 years ago Thursday.

"Here they are, mourning another anniversary of the death of their daughter and listening to the word 'pardon' and 'Karla Homolka' in the same breath, it's very, very difficult for them," said Danson.

"For both families, it will always be forever difficult to come to grips with the loss that they've endured. It does nothing but bring them anguish and despair."

There was no evidence that Homolka had sought to apply for a pardon next month.

But Danson said "there's no question that Karla Homolka was the focal point" of the push to change the pardon process.

After serving her prison sentence, Homolka first lived in Quebec and gave birth to a child. She now resides outside of the country.

With files from The Canadian Press