Senator Patrick Brazeau has already made history as one of the youngest people ever appointed to the upper chamber.

If the Senate agrees Tuesday to force him to take a leave of absence, he'll make history again by joining another exclusive club: senators who have been shunned by their peers.

No one who's been forced to take a break from the Senate has ended up being expelled; those who have come close usually pre-empt that step by resigning first.

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That could be little more than an attempt to save face and the procedural bother of kicking them out, but resigning also has a financial benefit: senators who are expelled don't get a pension. If they resign, they do.

Brazeau is free on bail and facing assault and sexual assault charges after being arrested last week at his home in Gatineau, Que. He's been kicked out of the Conservative caucus; on Tuesday, the Senate will determine his immediate future.

While he continues to sit as an independent, the charges give the Senate the ability to force him to take a leave of absence and curtail access to his expense account.

Senate Majority Leader Marjory LeBreton is expected to introduce a motion Tuesday to do exactly that.

Over the course of the Senate's 146-year history, some 199 senators have resigned, many for health reasons or to take another job. Only a handful have taken a leave of absence after a run-in with the law.

Liberal Senator Raymond Lavigne resigned in March 2011, 10 days after he was found guilty of breach of trust and fraud for claiming travel expenses for trips taken by his staff and having his staff do work on his personal farm on the taxpayer's dime.

He was later sentenced to six months in prison and six months under house arrest, a sentence that's currently under appeal.

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Progressive Conservative Senator Eric Berntson resigned his seat in 2000 after a fraud conviction related to his time as a provincial legislator in Saskatchewan.

He was sentenced to a year in jail and appealed his conviction all the way to the Supreme Court.

Both men could have faced expulsion from the Senate because of their convictions, but both resigned before that step could be contemplated.

At least eight other senators have resigned because they didn't show up for two Senate sessions in row, most doing so in the very early days of the institution. Breaking that rule gives the Senate the option of declaring a seat vacant.

The most recent senator to be disciplined for poor attendance was Liberal Andrew Thompson, who was suspended in 1998 after it was revealed he showed up for work only 47 times in 14 years. He claimed it was for medical reasons.

Thompson was stripped of his salary and benefits, but resigned, allowing him to hold on to his pension.

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Access to a pension was one of the hot issues when Brazeau was appointed to the Senate by Prime Minister Stephen Harper in 2008. Brazeau was 34 years old at the time, and the fact he'd be eligible for a government pension at the age of 40 drew immediate outcry.

He's eligible for a pension in 2015, after serving six years, even if he's on forced leave for some of that time.

"We don't think you should get an income for life when you're 40 because you actually worked four of six years; that would be a real travesty," said Gregory Thomas, federal director of the Canadian Taxpayers Federation.

"But it's important not to rush to judgment. Senator Brazeau has not been convicted of anything and he's entitled to a fair trial."

The forced leave of absence allows Brazeau access to his $132,000-a-year salary, but allows the Senate to cut off his expense account. That rule was enacted following Lavigne's case; while on leave, it was revealed he was racking up $32,000 for various expenses.

Brazeau remains a member of the Senate as his case winds it way through the legal system, which means he's able to attend proceedings with permission.

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His next court appearance is scheduled March 22.