A question in Parliament about judicial independence morphed into a smear of a Liberal MP, then erupted into one of the nastiest spats in months.

Outraged Liberal MPs drowned out Prime Minister Stephen Harper with chants of "shame!" on Wednesday as Harper  -- instead of answering a question on judicial independence -- tried to read from a newspaper article that links a Liberal MP's in-law to the Air India investigation.

The Vancouver Sun story said that Darshan Singh Saini, father-in-law of 29-year-old Ontario MP Navdeep Bains, is on a list of potential RCMP witnesses in connection with the 1985 Air India bombing that killed 329 people.

According to the article, Saini is a one-time Ontario spokesman for Babbar Khalsa (Panthak), a Sikh fundamentalist group. He is also an active Liberal.

The RCMP would interview Saini and other witnesses through investigative hearings made possible by the Anti-Terror Act. Those hearings allow the authorities to compel people to testify.

On March 1, that provision of the act will die unless Parliament decides otherwise.

The Liberals are opposed to a three-year extension of that provision, along with one that allows for preventative detention for 72 hours. The preventative detention clause has not been used to this point.

The NDP and Bloc Quebecois also support allowing the two clauses to fade out.

Ontario Liberal MP Bill Graham demanded that Harper "apologize and withdraw what was obviously going to be a drive-by smear."

Liberal MP Ralph Goodale shot back at Harper: "The prime minister's allegations are simply beneath contempt.

"The prime minister has attempted in this House to impugn the character and reputation of an honourable member of Parliament. That is absolutely unacceptable."

He also asked Harper to withdraw the statement.

An unrepentant Harper continued to attack the Liberals.

"Everyone knows that the entire front bench of the Liberal party supported these laws until two weeks ago, when the leader of the Liberal party started playing caucus games with the safety and security of Canadians. He should be ashamed of himself," he said.

Judicial independence

The flap grew out of an exchange between Liberal Leader Stephane Dion and Harper on the issue of judicial independence.

The Canadian Judicial Council issued a statement on Tuesday that criticized the way the Conservatives propose to change how judges are selected.

"Because the majority of voting members are now appointed by the Minister, the advisory committees may neither be, nor seen to be, fully independent of the government. This puts in peril the concept of an independent body that advises the government on who is best qualified to be a judge," said the statement.

"Will the prime minister stop attacking the independence of the judiciary?" Dion asked.

"The Liberal Party opposes the change we made, which is to give the police a voice in this process," Harper said.

"I'm not surprised, given what I'm reading in the Vancouver Sun today, when I read this is how the Liberal Party makes decisions."

As he started to read from the article, the shouting began.

Dion said afterward that one reason he opposes the hearings is the damage they can do to witnesses -- as evidenced by what happened to Saini, even though investigative hearings are supposed to be confidential.

"It's an additional consideration that (confirms to) us that there is a problem with that because it's smearing the reputation of somebody like this,'' he told reporters.

"When this tragic event took place, I was nine years old. The only think on my mind was playing hockey," Bains told reporters afterwards.

He said his father-in-law co-operated with the authorities 21 years ago and would do so again if required.

Bains also said the man shouldn't be smeared in public.

"You're playing with people's lives here, people's families. My father-in-law had heart surgery two months ago. This is the last thing he needs to hear about or see about.''

Goodale explains

Goodale told CTV Newsnet's Mike Duffy Live that one reason his party is upset is because Harper smuggled the reference in on an unrelated question about the judiciary.

The story was in a package of daily news clippings called Quorum, which goes to all MPs.

"It was very clear the prime minister was doing two things. He was casting some very serious aspersions about Mr. Bains ... and secondly, the implication that somehow the decision-making process within the Liberal Party is shaped by some family connection on this very serious issue on what is the right security law for Canada."

The Liberals' decision on the Anti-Terror Act clauses is based on analysis, he said.

"The Conservatives treat this not as a substantive issue of important public policy, but some cheap gimmick to get votes."

Jacques Shore, a lawyer for the Air India families, told Mike Duffy Live that he believes the Liberals didn't have any idea about this clause.

"The concern we have is ... are we going to find ourselves with an unintended consequence?" he said.

Dr. Bal Gupta of the Victims Families Association said: "It will hamper very seriously the ongoing investigation of the Air India tragedy."

Bev Busson, the acting commissioner of the RCMP, has also asked for the provisions to be extended.

With a report from CTV's Robert Fife and files from The Canadian Press