Abstentions are generally hard to assess. Unless an MP is sitting in the House of Commons when a standing vote is conducted or announces that they will be abstaining, it’s not immediately obvious whether an MP has declined to vote for some reason of viewpoint or simply because they had another commitment and their vote was not going to be pivotal. It’s probably fair to say that MPs have abstained from voting for principled reasons without us ever knowing. (The last purposeful abstentions I can remember were on asbestos in 2011. Steven Fletcher abstained on an assisted-suicide bill in 2010.)

Of course, dissent from the party line is not generally encouraged in our parliamentary culture. Most particularly on major matters of policy (the government viewed last night’s vote to be a confidence vote).

All of which makes Irwin Cotler’s principled abstention last night from the Iraq vote—coming as it did with a full explanation—a relatively novel happenstance.

“I have written ad nauseam almost on the responsibility to protect in general and in particular with regards to Syria … I was on record as, not only Canada joining an international coalition, but asking Canada to lead that coalition, to convene a UN security council urgent meeting, et cetera, et cetera. Therefore, I would have generally supported a resolution of that kind,” Cotler told me this afternoon. “So why wouldn’t I support something that supports my position? Well the answer is because this does not support it, but turns R2P on its head. Harper took the astonishing position to say that … with regards to Syria, if we’re going to go into Syria then it’ll be contingent on Assad’s agreement. As I said, this not only turns R2P on its head, it’s asking the criminal who should be in the docket or the accused for permission for us to engage in the very international military operation that he’s asking us to support. To me that not only was the theatre of the absurd on Harper’s part, but in fact it evinced a lack of understanding of the whole initiative that he was speaking about. And then to invoke the UN security council resolution … when in fact there was no UN security council resolution showed, again, a lack of understanding.”

This is actually not the first time Cotler has abstained for a reason of principle. In 2007, he abstained from a vote on anti-terror legislation (he followed that vote with an op-ed).

But Cotler’s was not the only interesting vote last night.

First, having publicly wrestled with his decision beforehand, Independent MP Brent Rathgeber voted in favour of the resolution.

Meanwhile, the NDP’s Charlie Angus is apparently unimpressed with the fact that the Green caucus (population: two) split on the Iraq resolution. (Whenever the NDP fusses over party unity, I’m reminded of Jack Layton’s decision to allow a free vote on the gun registry.) While Elizabeth May voted against, Bruce Hyer voted in favour, a decision he explains here (he did not speak to the resolution in the House).

It’s probably worth noting that if parties should be expected to require unanimity on votes pertaining to war, the three major parties in Britain would have to be considered failures.