A look at the pros and cons of the voting system said to be favoured by Justin Trudeau

Justin Trudeau has promised that last fall's federal election will be the last conducted under the first-past-the-post voting system.

In the past, the prime minister has expressed a preference for replacing FPTP with a system in which voters rank their choices on the ballot, although he has since said he is also open to some form of proportional representation (PR).

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Under a ranked ballot, voters mark their first, second and subsequent choices. If no candidate wins more than 50 per cent of the vote, the contender with the fewest votes is dropped from the ballot and his or her supporters' second choices are counted. That continues until one candidate emerges with a majority.

Ranked balloting remains one of the options under consideration by a Commons committee, which resumes its study of potential new electoral models next week.

Here's a look at the pros and cons of ranked ballots:

Pros

• Relatively easy for voters to understand, less complicated than PR models.
• Relatively easy to implement, would not require redistribution of riding boundaries or an increase in the number of MPs.
• Ensures no candidate wins a seat without garnering more than 50 per cent of the vote.
• Reduces the need for strategic voting. Voters can follow their hearts and rank smaller parties first, without fear that they're "wasting" their votes on parties with no hope of forming government or that they're inadvertently helping a party they don't want to win.
• Compels parties to try to broaden their appeal to attract second choice support.

Cons

• Does not result in a distribution of seats proportional to each party's share of the popular vote. Majorities can still be won with less than 50 per cent of the vote.
• One candidate in each riding will win; everyone else loses. Voters whose first choices lose could still feel their votes didn't count.
• Could make it harder for fledgling parties to break through and win a seat. Under FPTP, a small party can win a seat with less than 40 per cent of the vote. Under a ranked ballot, it would have to win more than 50 per cent.